aftermarket exhaust comparison with hp numbers

The August 2010 Dirt Bike magazine did a comparison of popular aftermarket exhaust systems for the CRF450X. They added a K&N filter and each exhaust system and compared it to a completely stock bike.

The ran each one on the Dyno and checked the weight

The following is a summary:

MAX HP..................................Weight reduction..........................Sound

Stock

41.16

FMF TI Powercore

43.69....................................2 lb 14 oz.........................borderline noisy

Pro Circuit T4S

43.29...................................2 lb 2 oz........................Loudest pipe tested

Leo Vince Enduro Sport

43.03..........................................8 oz.....One of the quietest pipes tested

Vance and Hines XCR

42.29.....................................1 lb 8 oz..............................middle range

Dr. D

42.91....................................2 lb 7 oz............................Almost too loud

Jardine RT99

43.52....................................few oz.................A little loud for trail riding

Yoshimura RS2

44.0....................................10 oz...............................second quietest

There was a lot of other information in the article regarding low end and midrange power increases and throttle response. Overall, it was a really thorough, well done article.

Thanks for sharing, ive been curious about these numbers for a while now.

Im assuming that they are all slip on systems and jetted to suit?

Ive been thinking about getting a full FMF 4.1 system or Yoshi. I know the Yoshi would be the pick if i was chasing power but realy i just want to save a couple lb's with a nice exhaust note. Cant argue with the FMF quality and price really.

did the newer x's get a new cam? i thought i remember the stock x having around 48 hp from a dirt rider test in around 05 or 06?

Their noise ratings are...well, quite disappointing. Noisy, more noisy, not quite as noisy...come on. Give me actual db ratings. I don't want the author's opinion, they're providing facts for the power...do the same for the noise rating.

Good info for the power ratings though. Especially since I'm looking at replacing my exhaust. :smirk:

Stock being 41 and a pipe with filter giving you 43. Thats a pretty good increase, imagine if the box was open an bike jetted to run with mods. Im sure there would be an even better increase.

I remember a dirt rider from like 2000 or 2001 covering Ezra Lusk's 250 2stroke, it was putting out 60+hp and the article was going into all the technical crap done to the bike and how it had a box of electronics that recorded the engine's performance. I could not imagine that kind of power on two wheels being as light as a factory bike.

Thanks for sharing, ive been curious about these numbers for a while now.

Im assuming that they are all slip on systems and jetted to suit?

Ive been thinking about getting a full FMF 4.1 system or Yoshi. I know the Yoshi would be the pick if i was chasing power but realy i just want to save a couple lb's with a nice exhaust note. Cant argue with the FMF quality and price really.

the yoshi ain't that quiet... don't ask me how i know...

Thanks for sharing, ive been curious about these numbers for a while now.

Im assuming that they are all slip on systems and jetted to suit?

Ive been thinking about getting a full FMF 4.1 system or Yoshi. I know the Yoshi would be the pick if i was chasing power but realy i just want to save a couple lb's with a nice exhaust note. Cant argue with the FMF quality and price really.

All of the systems tested except one were full systems. Sorry, I can't remember which one (that manufacturer didn't sell a head pipe for the X).

Their noise ratings are...well, quite disappointing. Noisy, more noisy, not quite as noisy...come on. Give me actual db ratings. I don't want the author's opinion, they're providing facts for the power...do the same for the noise rating.

Good info for the power ratings though. Especially since I'm looking at replacing my exhaust. :smirk:

Dirt Bike said that they could provide db ratings for each of the systems but, in their opinion, that wasn't as meaningful as subjective ratings from the riders. Their experience has been that one pipe might blow a 96 db in the test and another 99 and the 99 will actually sound less noisy in actual riding conditions.

The previous issue of Dirtbike had the off-road shoot out and they fitted each bike with an FMF Q4 silencer. Using the FMF Dyno they showed the 450x at around 49hp. That sounded a little high to me for a stock bike.

The previous issue of Dirtbike had the off-road shoot out and they fitted each bike with an FMF Q4 silencer. Using the FMF Dyno they showed the 450x at around 49hp. That sounded a little high to me for a stock bike.

Thats a big claim i agree. Maybe with supporting mod's on 100% race gas.

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