Exhaust Information Page

This page was originally written in 2001 and is oriented towards the RC51 specifically, but the info, dated as it is, still pretty much rings true for all the brands mentioned.

Due to the steady influx of e-mails of people asking for my "opinion" on slip-on exhausts for the RC51 I have written below some of my thoughts and experiences over the years based on over 3 decades of extensive carb & Fi tuning as well as credible reports shared from other professional tuners.

I would like to start off by saying that the addition of the PowerCommander (PCIII USB or the new PCV) is more important than any choice of exhaust. Even if you are running the stock exhaust cans your bike will benefit from the Power Commander in terms of improved throttle response and more linear power delivery. More horsepower is generally a by-product of those two traits, but is secondary in my opinion to what the Power Commander is actually offering.

Second I would like to say that purchasing an exhaust is above everything else a matter of personal preference as well as financial ability. You should buy an exhaust based on what you like & what you can afford, but keep in mind that more expensive isn't always better. Contrary to popular myth all slip-ons are not created equal, Some cans due to different length cores, core diameters, length & bends in the mid-pipes & even density of the packing can give different results with peaks & valleys at different points along the rev range. My only guideline to you would be: Don't buy an exhaust for looks alone. Make sure that whatever mod you are doing to your bike doesn't decrease performance by hindering horsepower or adding un-needed weight like shotgun slip-ons etc especially on a bike like the RC51 which is relatively low horsepower and quite heavy where every bit of power not only helps, but can be used. If you have a 200hp BMW S1000RR it is not so much a problem if you lose a couple horsepower here or there, but when you only have 120rwhp or less like an SV650 then you really want to do your research to make sure you are not robbing yourself of performance.

A little hint I would like to add. If the exhaust you are looking at uses the same size tubing to run from the collector to the exhaust cannister (mid-pipe) then it most likely is not going to be the best choice for performance. Premium exhaust manufacturers (Akrapovich, Harris, Moriwaki, Sato) that truly do the R&D to tune the exhaust flow & reversion waves will use tapered sections of tubing that expand as they move toward the cannister while cheap ass companies simply bend a one size piece of tubing to make it fit the bike...

Finally, no exhaust is 100% perfect. No matter how good or reputable a company is they are going to have a certain amount of failures in the field. Leaking cans, loose rivets or even a mis-shipped part in your kit are all things you can almost expect at some point. The issue then becomes customer service & who takes care of their problems with professional results not just a temporary band-aid to the problem until the next sucker comes along. Personally I feel that if a company is constantly doing development work & trying new things they should be given some leniency if something goes wrong especially in contrast to those companies that never do R&D and have been making exhausts the same way for a decade or more & are still having the same problems today that they had 10 or 20 years ago...

For all you friggin retards that want to hear a .wav file or video of the exhaust sound for comparisons, quit reading now and go somewhere else. Do you really think you can honestly hear an accurate reproduction of how an exhaust sounds through recorded media on the web? I could record the same exhaust from 2 different angles or different distances or with different recorders and you would think it was two completely different exhaust systems. Sound files are a novelty at best & if you are just basing your exhaust purchase on sound alone you won’t be interested in the info I have compiled below

There are 4 main topics addressed on this page:
1. Quality & characteristics of different brands of exhausts
2. Slip-ons vs Full systems
3. Wrapping & coating the headers
4. The new 2-1 exhaust fad

I've had Microns, Moriwaki's & Erions (two sets) on my personal RC51. All of them are really great cans with different affects on the engines output. the Erions are qood quality with a durable finish & without a doubt one of the best bargains for the money, but their fitment onto the bike left a little to be desired on two different installs I have done and performance was bleak compared to properly tuned exhaust systems. The BEST I have used are the Sato Exhausts (aka babyface in Japan) which I used long term and eventually sold the RC51 with. I continued to use Sato Racing products on all my new bikes up to the point they decided to stop producing exhausts and focus their efforts on their CNC parts business. Up to that point they still continued to dominate the dyno comparison tests & their build quality was some of the absolute best in the world. Couple those two very important qualities with the fact that the US Distributor also sets the bar by which all other companies are judged for Customer Service & also gives away free dyno tuned Powercommander maps for all the products they sell (about a $300 value for the map) & you just cannot argue that these were the best exhausts available to us here in the USA and possibly the world. Unfortunately they have been discontinued and sold out worldwide for several years now. Anyway, The Sato's exhausts produced phenomenal torque numbers with a very unique configuration of long stepped mid-pipes with short cans & large cores. Even without a Powercommander the Sato's produce mid-range gains much higher than any other exhaust. Of course the whole concept is that it is a package deal as the Powercommander allows you to fine tune your fueling to match the exhaust flow & I firmly believe that every exhaust distributor should provide free mapping support for the exhaust they sell! I mean it should simply be an industry standard.

Additional notes on Sato's: they are were available in 3 mounting configurations in both Titanium cans and a Carbon Fiber version that is proven to hold up to the V-twin pulses that caused many other brands of carbon to fail.
Banzai mount-very high mount right up underneath the tail section (no passenger pegs)
Low mount-allows the use of the passenger pegs & in addition also produces the most power of any slip-on tested to date
High mount-these were the originally designed for the 2000-2001 RC51 & were phased out by the advent of the Banzai mount.

MotoGP style thinline canisters were also available in 2 different lengths, but I gotta tell ya these are just plain obnoxious. Not just on the RC51, but other bikes as well. They are so loud that nobody wants to ride around you and there is nothing cool about them after the first 30 minutes of riding. They attract way too much unwanted attention from cops, draw the ire of your neignbors everytime you fire up your bike and they run hot because of a limited amount of packing inside which also means they need to be repacked much more often than a larger exhaust can that holds more packing material.

On to some other brands, the Leo Vinci's are another pretty good exhaust, but I do not feel they offer the same value for the dollar as the Sato's do as they are fairly expensive & do not deliver the same performance numbers, but are still much better than average. Apparently there have been a lot of issues with distribution and customer service in the US over the last several years as they struggle to retain a proper distributor which brings the future of their products being available into question.

The Microns were the first set of slip-ons I installed on the RC & are well made, have a long standing reputation for quality & have unique lateral end cap mounts that provide secure fastening/easy access, but the high mount configuration is an abomination. It was designed purely to fit the bike as an aesthetic afterthought & performance suffers for it as does foot room. I believe that Micron has lost sight of their performance roots & have decided to go after the poser market spending their resources on polished colored cans & colored carbon fiber instead of trying to keep pace with the cutting edge exhaust manufacturers that are truly getting more power out of their exhausts instead of just claiming to. The Erions are alot of bang for the buck with decent power gains & the gloss black powdercoated can is absolutely gorgeous. I have used Erions on every 900RR I have ever owned & recommend them regularly for those riders who are financially challenged. You will be hard pressed to find a better USA made exhaust, but they still pale in comparison to the Japanese products. The Moriwaki's build quality is superb, the welds are meticulously done & power gains are easily seen on the dyno & felt through the seat, however with the advent of the new Sato exhausts I have a new favorite. They produce all the low end power that the Mori's had as well as a super healthy mid-range torque curve & with the Fi mappings that we have available there is truly nothing else like them on the market! It must also be pointed out that Moriwaki now has a standard mount Slip-on Exhaust that produce power very similar to the Sato's, not a bad choice if you are not sold on the looks of the Sato's & still want premium power out of your exhaust. In addition Sato continues their R&D long after they have already raised the performance bar to a new level. They actually redesigned the low-mounts after first releasing them so that one core is smaller than the other to better tune the gas flow/back pressure yielding even more gains over what was already the best performance increase on the market.

Micron also had a full system for the RC51, but more than one source complained of it being ill fitting & difficult to install.

I have very little hands-on tuning experience with
Arrow exhausts, but I have seen their craftsmanship & design which used to be known for both creativivity and quality, however they have really been slipping as of the original writing of this article (2002). Not that it is pertinent to this exhaust page,but the Arrow rearsets on my RC flexed so much that the eyelet bolt on the master cylinder plunger gouged into my swingarm & many owners have had to send their cans back several times due to severe exhaust leaks around the end caps. To me these types of flaws are just inexcusable considering the technology (& money) today's companies have at their disposal for R&D. The Arrow power curves as seen on the dyno charts are the worst when compared to the other mainstream exhaust manufacturers as they provide a small peaky mid-range, but lose all low end response & topend suffers as well.

Yoshimura is family related to Moriwaki so it is no surprise that the dyno charts are very similar in the fact that both Yoshimura & Moriwaki produce horsepower in the low & midrange where the RC51 needed the power the most. Yoshimura also has a reasonably priced full system available. This another one where bang for the buck is a very substantial value. Yoshimura also offers several of their models with street baffles for a much quieter exhaust tone. Most importantly in this current day and age when most companies have completely forgotten about the RC51 Yoshimura is still supplying exhausts for this bike and they are still a good quality, consistently made product even if they aren't the best performing exhaust choice.

Harris has been another one of those companies that usually puts out better than average products, but as time has gone on more & more owners have not been totally satisfied with their RC51 exhaust cans. Many of them have had problems with insufficient packing material causing the cannisters to badly discolor under normal road use. They do use tapered mid-pipes & do R&D work to make sure that performance gains are actually there before they market their systems, but the gains on the RC51 from their slip-ons are just mildly improved over stock, but they do have a decent hit right at the very top of the rev range, although in truth not many of us actually spend much time with the revs that high.

Hindle products have been pretty much hit & miss in my experience I have bolted up the same model of system to identical bikes & sometimes they fit great & sometimes they don't. I've never really been impressed with any of their power gains, not that they are poor performing they just don't really stand out when compared to the competition & finally they just look cheap without much design effort, kind of like just bend some tubing & slap on a simple sleeve over a core cannister. Now I'm not trying to advocate form over function, but they could certainly use a little creativity or something to use as a selling point since their performance numbers are nominal.

D&D has a good reputation for build quality, their chrome plating is second to none & they can truly withstand crash damage far better than other manufacturers, of course they are also quite heavy. Their carbon fiber isn't as high quality as other brands & fades quickly, in the process it also becomes quite brittle. It seems with all their slip-ons for various models of bikes, performance is increased but only marginally. Decent can, especially for the money, but there are better choices out there.

M4 exhausts on the RC51 are pretty good bang for the buck too, but they aren't anything special & performance gains are just inline with the rest of the low end exhaust systems. I will say though that since this article was originally written in 2001 that M4 has come a very long way towards improving their performance & quality of their currently offered exhausts. They are now in 2014 without a doubt some of the best value for the dollar domestic USA made exhausts on the market and they have also improved the aesthetics of the exhaust to go along with the built quality and performance improvements. I am personally using their products on several of my bikes where I didn't want to spend a couple thousand dollars on an Akra system including my trusty old F4i and my new to me Gen 4 ZX-10R Track Bike.

Although I was not originally very keen on the idea of Jardine trying to get in the modern sportbike market, I must say that I am fairly impressed with the quality of their product. Only recently have I heard any negative feedback from owners, but the cans I have seen in person appear to be very well constructed. Jardine also has both street baffles & race baffles as an option. More info on their 2-1 systems below

Akrapovics are touted as the premier exhaust manufacturer in the world and provide a lot of exhausts for factory race teams all the way up to MotoGP prototypes. They are also the most expensive & although most people that bought them will never admit they made a mistake & will attest till the day they die that they are the best cans in the world, I have had several Akra owners tell me that while they are put together with the precision & care of a NASA scientist, they really aren't worth the money in what you get for performance advantages on an RC51 with the exception of some increased top-end numbers, but come'on how often do you ride around at full throttle redlining the bike at 10,200rpm??? It makes a lot more sense to buy a slip-on that gives you the gains where you need it the most in the low & mid-range.
Update for 2011 Akra appears to have discontinued both their slip-on & full systems for the RC51.

It should be pointed out that while I am not a fan of the Akra products for the RC51 I still firmly believe they are one of if not the premier exhaust manufacturer in the world. Their exhausts are pricey, but are of exceptional build quality and always fit together perfectly. They also routinely make a lot of exhausts for Factory Race Teams at the World level of competition which says a lot considering there are more than one brand of exhaust out there that pay for sponsorship rights to a race team. More on that further down the page...

HMF & Muzzy slip-ons. I have not had any personal experience with HMF, however I have had several reports form owners stating that their cans look pretty worn & that performance gains are nominal. The Muzzy cans I have seen were less than a year old & looked like they had been dragged through Afghanistan literally falling apart (pure crap compared to the better brands that are available)

Once again in my opinion & since this is my site I have no reservations about openly saying that I don't like Two Brothers products. They are ill-fitting, leak way too often & I have personally seen several of the carbon fiber cans burn themselves crispy & not just on twin cylinder machines. Most importantly I see no real advantages in the horsepower gains on most of their systems that distinguishes their numbers from any other manufacturer. Bang for the buck is laughable, as they are way too pricey for what ya get. On the RC however they do turn out some pretty impressive dyno numbers even though the general consensus is their quality is still sub par. In my experience the only people that ever praise Two Brothers products are the people that have never owned any other brand. Find someone that has owned a Two Brothers product and then purchased an AKRA or Sato or Graves or basically any Japanese made exhaust and they will adamantly tell you the difference in quality is drastic.

There is alot of controversy over manufacturers like Black Widow, Blue Flame, ART, Wolf, MIG, Renegade & various other obscure & not well known companies that are marketing cans for the RC51 & most of it revolves around negative feedback from people with previous experience. In the beginning I firmly believed that there just wasn't enough credible feedback on most of those companies to pass judgment on them even though I blasted many of them pretty hard publicly on the forums, but I had done enough research & hands-on at that point to basically say with confidence that they were mostly crap... Anytime you stray from the well known reputable companies it's always a gamble to spend your money with them...
UPDATE: most of these companies are now out of business. Guess I was right all along.

Pretty much any exhaust that comes out of England or Italy is crap. People are always quick to point out that Termignoni is from Italy and while Termi's are definitely at the top of the price list they are also at the top of the crap list IMO. They have to be the worst value for the dollar there is as their exhausts look like they were slagged together by some kid in highschool shop class, but you don't have to take my word for it the next time you see a Termi exhaust on a bike sitting outside the local Starbucks take a good look at it and you will see the poor welds and slag marks for yourself. For those of you that will say something really stupid like "well Rossi's M1 MotoGP bike used Termi's" let me retort with no it didn't those exhausts were made by a completely different manufacturer and had a Termi badge stuck on them just like the American Honda Factory HRC RC51 racebikes that Hayden & Duhamel ran had Akrapovic exhausts with Jardine badges. When it comes to big corporate sponsorship deals with race teams you cannot trust much of anything you see...

Here's a pic solely for the sake of comparison showing a Sato Racing Exhaust on the left with a Termignoni exhaust on the right
Night & Day difference in the quality of welds let alone fit & finish...

Now we switch to the Slip-ons versus Full Systems argument

The short of it is with the RC51 (for other bikes keep reading) I think that Slip-ons are more than satisfactory for most applications & I only recommend Full Systems if you intend to do internal engine modifications such as pistons & cams etc...

Exhaust dynamics are a science all their own & then you compound that with jetting or Fi mapping as it is coming to nowadays and you have a lot of variables in the finished product. There are so many factors involved in exhaust building: the diameter of the headpipes as well as the radius of the bends directly affect the flow characteristics of the motor, but contrary to popular myth the angle of the bends in an exhaust system aren't near as critical to affecting the performance in either direction as the actual length/diameter of the tubing is or the angles of bifurcation at any collector are. In addition to that there are pulse shockwaves from the valves that need to be tuned to make sure that the pulse lasts long enough to get all the way through the pipe without kicking back and causing interference with the gasses that are trying to escape if that happens then your engine is robbed of horsepower because it has to work harder to get the gasses expelled from the motor and pulse kickback can yield results varying from nothing more than a slight hiccup at a specific rpm to a lull spot that lasts for several thousand rpms in the range. I'm no scientific genius by any stretch of the imagination and I'm sure there are others that can explain it much more thoroughly than I can, but my simple & generic explanation will have to do for now.

All Slip-ons are not created equal! Just as the shape & size of the headpipes affect the gas flow on a similar note the diameter of the cans core as well as the length of the can , the length & shape of the mid-pipes & even the material used for packing will alter the pulses within the system. Slip-ons generally add topend horsepower in exchange for losses in the lowend & frequently mid range too. These can usually be ironed out through rejetting (mapping for you Fi guys), but horsepower is always a trade off somewhere. good midrange usually means less lowend & very little improvement in top end while a system or slip-on tuned for topend will typically result in less low & mid range etc... Look at some of the charts for the Moriwaki Slip-ons, like this one for the Moriwaki versus Arrow Slip-ons they are very unique in the respect that they provide a monster gain in the low rev range & another great gain on the top end, but the mid range does suffer some over other brands of Slip-ons which just further proves my point that it's always a trade off.

Full systems: Again, everything about performance is a trade off. For example you can get cams that offers a strong top end, a good top end with a good mid-range or a great mid-range with a mediocre low end and top end etc... What you can't get is a cam design (at least not with a conventional cam phasing) that allows you maximum hp in all three areas (low, mid & high) of the rev range. Full exhausts are the same. Many full exhausts offer a better top end hit of power at the expense of mid-range performance and usually sacrificing low end power altogether usually along with some throttle response too. There is where you have to ask yourself what you really need in your bike? Do you really spend that much time at redline with the throttle pinned to the stop or would you rather prefer more mid-range power on tap where you spend the majority of your ride time etc... After you answer that question then you need to do some research and decide which full system is good for you. Most do offer better peak gains, but there are exceptions to the rule and in some cases a full system can even hurt performance of a stock bike especially if it is a Full-On Race sytem derived from a Factory Superbike team. I've seen full systems taken from Ex-Factory Superbikes of several different model bikes that actually lose hp when installed on a production based bike like you or I can buy from a dealer. You might score some poser points, but won't gain the power in most cases when you install an exhaust tuned for a 200+ hp race motor on your production based streetbike.

Most Full systems however marketed for production streetbikes or even for mildly tuned race motors will yield horsepower gains throughout the entire rev range so even though it might not be as much mid-range performance as a certain well designed slip-on it will most likely still make more power than a stock exhaust etc...

I've come this far I might as well go on with the Exhaust wrap... Exhaust wrapping your headpipes can alter the gas flow & even the reversion pulse waves in some cases. It can be beneficial for many stock exhaust headers when used with a slip-on as it tends to allow you to run stronger in the mid-range (after rejetting/mapping). It keeps the exhaust gasses hotter longer which makes them easier to expel out the pipes. We all know that the hotter something is the easier it flows... Problem is it is extremely difficult to get the jetting/mapping right after the wrapping mod & carbs specifically are a real pain in the ass usually requiring needles many times thinner and outside the typical range of off the shelf jet-kits... Also wrapping a Stainless Steel headpipe will rapidly deteriorate the pipe & if you wrap a ceramic coated header expect an ashy result within a relatively short time frame. OEM headers are no exception and as proven by Christopher Williams (of the Honda RC51 fans Facebook page) the damage can be quite catastrophic over time.

So in the event any of you follow up on this stuff I only suggest wrapping the stock headpipes due to their heavy construction... The extra heat generated inside the pipes by the wrap will eventually destroy the stock headpipes too, but this takes a very long time and you can usually find stock headpipes for sale just hanging in someone's garage... NOW THE KICKER: Although I have experienced gains by doing this mod on many different bikes with inline motors, I have not experienced any appreciable gains with it on the RC51. Now to clarify that statement let say that my first attempt was without the benefit of a Powercommander to alter the fueling & there were zero changes registered on the dyno with the addition of the exhaust wrap. I had intentions of trying it again later on, but simply never got around to it. It was effective at lowering engine bay temps read by an infrared thermometer. Let me also say that many RC51 owners have found it very beneficial to wrap the rear headpipe where it is in close proximity to the rear shock in an effort to keep the shock cooler from radiated heat & reduce shock fade. I tried that and noticed no perceivable difference whatsoever, but your results may differ. On a related subject let's discuss Jet Hot coatings: I do not have any actual experience with the jet-hot coating & the reviews I get from credible people that have had it done are diverse to say the least. I am relatively sure it is a worthwhile investment as in theory it should work great, but for me it's hard to beat a $50 roll of exhaust wrap combined with some dyno time...

All that being said the biggest problem is that many people that tend to do this kind of work don't take the time to alter the jetting or mapping properly or don't really understand how to properly jet their bike. They they have a cousin that jetted a bike once (followed the instructions, dropped in a jet kit on the Yamaha 4-Wheeler & now they are an expert) & don't actually have a clue to the principles of why you change needle heights or mixture screws etc... Then you get people saying "well I wrapped my exhaust & it doesn't do anything", but I'm sure you catch my drift.

The 2-1 exhaust fad

I disagree with the entire premise of this more midrange power with a 2-1 which keeps popping up on RC51 forums
update: the dyno charts are proving me right...

I have seen many 2-1 systems yield better topend hp & weaken the mid-range like on the Erion Superhawk & numerous Hawk GT systems.  That's not to say that with enough piping & tubing you could get just about any result ya want, but it will most likely be a point of diminishing return as the overall power output will most likely be significantly lower (if you were to purposely build an exhaust just to prove a point)

I firmly believe that on the HRC Superbikes that the extra length of piping is taking the jerk out of the mid-range making it a less powerful hit of power & thus more useable, but not "more" mid-range power. Along with that I suppose that top-end may be suffering some, but with 190hp on tap I guess you could stand to lose a couple here or there.

Either way I think alot of people are going to be dissapointed when the final product comes around & it doesn't give you this miraculous mid-range power gain that you have all been dreaming about.

Several manufacturers tried their hand at replicating the 2-1 exhaust for the RC51, none made a product truly worth mentioning in that regard.

Update 06/05/02: The Erion 2-1 full exhaust on the 02 bike is producing dismal power curves even worse than stock & has several issues with overheating the motor as well as scorching the single cannister.

Update 07/18/02: dyno charts of the Erion 2-1 with a terrible mid-range dip

Jardine has admitted that they are having problems with the mid-range with their 2-1 system & Arrow is being very tight lipped about their 2-1 after having made a big showing of the prototype many months ago which to me is most likely indicative of their failed attempts or at least performance issues stemming from the design.

UPDATE: Jardine has released their 2-1 full system & the performance numbers aren't bad, nothing spectacular, but no major drops in performance either. A few owners have commented that it leaves a flat spot in the mid-range, but overall with a retail price tag of $499 it sounds like a pretty good deal for those that want more performance than stock, less weight (credible reports have it at a whopping 19lbs of weight savings & a real world price of $390) & something fairly unique dyno chart for Jardine 2-1 another dyno chart for Jardine 2-1 supplied by an actual owner (the mid-range dip is pretty severe on this one). There have also been numerous issues of the welded tab breaking off on them as seen here 2-1 Jardine broke

One more thing I would like to add: I used to frequently get arguing e-mails sent to me by some upset viewer of this page stating that his brand X cans are the best he has ever had yada yada yada... Well until you have personally owned or experienced a premium exhaust like Moriwaki, Sato, AKRA or Hamaguchi you simply cannot understand what a good exhaust is! You may think your $900 exhaust slip-ons are the best thing since sliced bread because you paid so much for them or because they are loud (some people really use that for an arguement) & yes it did increase your horsepower, but then again you can remove the mufflers & run an open header & still see an increase in power... A premium exhaust not only gives you added performance, but you get high build quality as well not just one or the other or in some cases neither... All you have to do is look at the classifieds you see all kinds of exhaust for sale all the time like Two Brothers or Microns etc from people that are looking to "upgrade", but you rarely see Moriwaki, Sato or Akra exhausts for sale because nobody has a reason to get rid of them & there is nothing more to "upgrade" to. (just something to think about).

Feel free to contact me with any specific questions you might have & I will do my best to get you a researched answer. Or if you feel that any information on this page is blatantly wrong please contact me with proof otherwise.


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