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Quite frequently, posts arise here about slip-ons, headers, complete and altered systems; stock vs. true duals vs 2-1 etc etc etc and everyone (mostly system manufacturers) claim better performance, torque and horsepower if you go with them. Given the amount of time, research and even a few on here that have done comparisons, one would think raw data would be available for all to see and to decide on what they want. With few exceptions we see dyno sheets stating this and that vs. the stock setups they had prior but nothing on a grand scale. I suppose most will concede that 2-1 systems have more favorable numbers over other set ups but really by how much. The shear number of different applications is staggering and a crap header with an excellent slip-on may yield just as good numbers as a stepped header with so-so mufflers etc., yet there really are no real comparisons. Companies like Revzilla and others routinely review products that they handle but even then nothing empirical to back up their observations. I have put a ton of money into my 03-RKC. Tuner, auto tuner, cams, breather pipes slip-ons etc and im happy with it, but for people to really make an informed decision how best to dump their dollars into their bikes, wouldn't it be nice to go to some all encompassing chart and say, "if I put this on I can expect this and if I mate this up with that, we should be able to come close to this etc etc". With corporations, manufactures, and technologies available today, it really wouldn't be that hard would it?... ..Its cold up here in Canada and we Canucks tend to ponder the universe and bikes when we can't ride.
Lacking that empirical knowledge, the pucker on the pad is the really the best test for you and your bike. I have always listened to other folks reaction to the exhaust they are running and have never bought a pipe or pipes that hurt or didn't improve the bike's performance. I have, however, changed out a couple of systems that came on a bike to get better numbers. When people say true duals kill low end torque, listen because it is true and you don't need dyno numbers to prove it. The advantages of 2-1 is that each cylinder helps to pull the exhaust gases from the other.
Don't worry as even in Canada, winter doesn't last forever...It just seems that way.
Dyna Rider, well said and of course everyone has their preferences as did I. But in all fairness my bike is not stock any more. Would the 2-1 out perform the stock pipes and true duals? Most likely but I have put cams, turner and a few other goodies in that put it over the top of the 2-1s. Then again I have a road king and not a rice burning rocket. I can easily hang with the big boys. My point was though that the big manufactures don't do it. At least not openly. I just wondered why no one has. We have data on just about everything else. Would be nice.
theres several reputable dyno shops that publicizie their results of various mods/builds. Fuelmoto and GMR performance are my go to's for references on performance figures.
Lacking that empirical knowledge, the pucker on the pad is the really the best test for you and your bike. I have always listened to other folks reaction to the exhaust they are running and have never bought a pipe or pipes that hurt or didn't improve the bike's performance. I have, however, changed out a couple of systems that came on a bike to get better numbers. When people say true duals kill low end torque, listen because it is true and you don't need dyno numbers to prove it. The advantages of 2-1 is that each cylinder helps to pull the exhaust gases from the other.
Don't worry as even in Canada, winter doesn't last forever...It just seems that way.
the scavenging effect is less with the fewer number of cylinders. An eight cylinder sees more benefit while a vtwin...not so much. While some true duals loose bottom end they're not all created equal. A little research showed a good dualsystem with a steppedheader and louvered baffles will perform well. A 2 into 1 is usually easier to tune but again they're not all created equal either. More important to have the exhaust work with the rest of the components. There's no empirical data from manufactures of exhausts because they don't want you to know the truth and then you won't **** can your dual system and run out and buy a shiny new 2 into 1 because somebody said so. Why would my dyno guy who's been in the business for 20 plus years tell me to buy whatever system I like best? (He did give me suggestions on each though.) Because on the street I'd never feel the difference.
I have a 2-1 RB pipe on my Dyna. I love the way it looks and sounds. I had a Bassani 2-1 on it before the RB pipe and it made good HP numbers but I didn't like how loud it was or the black ceramic coating on the pipes as it showed every imperfection. I did a lot of engine work at the same time I installed both pipes, so I can't say that this pipe or that pipe gave me better numbers or even how much.
The dyno numbers depend on what kind of engine work was done. If you do cams and no head work, your numbers will obviously not be as good as with head work and no pipes in the world will change that. You may pick up a few ponies and ft lbs of torque from a new pipe and intake.
Some people are more sensitive to their bikes performance than others. If my dyna ran in the summer as well as it did in the winter, I wouldn't have started the engine mods. Some people cant see or feel the difference the bike has in different seasons. I have heard several people say, on this forum, that their bike runs the same year round regardless of season. If you feel that way then you aren't very aware of your bikes performance. My first mods were a big bore kit 88 to 95 cu in and 211 torque cams. It had great mid range power and you didn't have to change gears to go around someone. Most of all it is what ever makes you happy. I agree with Screaming beagle that manufactures don't want you to know the real numbers because they wouldn't sell as many exhausts if the public knew those numbers.
With just 2 cylinders, it would seen even more important that scavenging should help the engine breath better. I hate true duals after my experience with them and I personally think a 2-1-2 is a much better option and I can feel that in the seat.
Last edited by dyna rider; Feb 9, 2019 at 02:31 PM.
Reason: Add Pic
Good responses here from everyone and everyone has their own ideas to what they want and like to see and hear. My reason for true duals was to even out the heat so the right side wasn't always hotter than the left. Secondly I like the look and sound and make no mistake about it, I did research as best I could prior to it but in the same sense, I knew I was getting cams and a tuner/auto-tuner so I would be able to make up any low end loss and honestly that is the case. I have an 03 Road King Classic. 88 ci. 5 speed. Prior to installing all the goodies I would drop down a gear to pass another vehicle quickly. Now with the 510 cams, the true duals, breather, auto tuner, etc., this little 88 will rocket and I mean rocket past someone on the highway without the drop to forth. So Yes the 2-1s are best for savaging but I never liked the look and the heat associated with them on the right side. Not for a touring bike. Indecently I have an old SuperSport in the garage that has a 4-1 with a monster cannon on the right side. The 4-1 definitely blew away the stock pipes and on a café racer, it looks proper. Just my .02 on that.
The whole reason for this post originally was to perhaps wonder given all the technology, all the manufacturers of parts and the like, that someone, some manufacturer, some forum etc, might have had the opportunity to post comparison results. We see YouTube after YouTube of putting on different pipes :this vrs that but not much on true data as to how they perform and I have to believe its out there. Maybe just not for our eyes.
So a stock 96 inch with a 2 into 1, made 8 horsepower more than a than slip on mufflers.
On a 88 built to a 98, head work and cams there was a 5 horsepower difference between true duals and a 2 into 1.
Good info.
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Is there any legitimate Exhaust Data?
