Off-road bikes balance a fine line of durability versus performance and sound versus power output. In order to excel in one area, the other seems to have to suffer. All of the pipes presented here balance these aspects of exhaust differently; whether it’s big power or stealth quiet, there is something here for everyone. The only requirements we insisted these pipes meet were to be off-road-legal: Pass a 96-decibel sound test and have a USFS-approved spark arrestor.The manufacturers were also allowed to send an additional pipe for one of several bikes for us to gain an additional riding impression. These, combined with the information presented in testing the same brand’s system for the WR, will hopefully give you a good idea of what power characteristics pipe manufacturers are striving for in their design. And thus offer you insight into purchasing a pipe for your own bike not necessarily just the Yamaha WR450.
WR450F Evolution Full SystemFit and Finish: NASA envies this pipe. The craftsmanship in Akrapovic’s exhaust systems are first-rate, and anyone with a keen eye for high-quality welds will appreciate it. Install gets a B-it’s more involved than some because there are more pieces, but it fits exceptionally well.On the Trail: This pipe addressed the sign-off top-end feel that is characteristic of the stock system. It has good, smooth drive like stock, until the mid, where it is boosted with strong power in the upper mid through the top-end. It lets you run the gears longer than stock. The delivery is smooth and not overly exciting; it’s always usable and linear. It may not be a rip-your-arm-out-of-their-sockets monster, but it does the job extremely well. The Akrapovic is a favorite for its mix of beauty, durability and performance.
Contact: www.akrapovic-exhaust.com; www.PhillipsMotorsportGroup.com;
Construction: Full titanium with carbon-fiber heat shield and muffler mounting brackets
Weight: Full system, 5.2 lb
Sound: 94.7 dbStock Yamaha
Weight: Muffler only, 7.34 lb; full system, 8.92 lb
Sound: 89.5 db
Fit and Finish: Indestructible-lasts forever and fits the bike superbly.
On the Trail: As tested with the smallest muffler plug removed (and only the smallest plug along with the throttle stop replaced with YZ part, the gray ignition wire disconnected and the airbox opened up), the stock system is super smooth all the way through the powerband, picking up quickly on bottom and pulling strong. It’s a little hiccupy with on/off throttle control through the mid. It stays quiet the whole time and prefers to be short-shifted, as it signs off on top with a definite “shift me now” feel.
WR450F EvoX Slip-on with Vortex InsertFit and Finish: The EvoX lined up well but not perfectly, and the split junction made install and removal easy, so we give it a B+ for mounting. The only downsides are some of the fasteners that come with the muffler are oddly sized and the end-cap bolts tended to work loose (we thread-locked ours). The muffler gets very hot because of the insert, which is a little unsettling.On the Trail: The EvoX is quiet like the stocker to the outside world, but the rider hears the bike. It has a good, smooth pull that is boosted over the stock power output a little everywhere yet is still linear and mellow. Top-end pull is long and smooth and feels like it revs out further on top. This pipe lets you twist the throttle farther and lets you feel the pull of the bike, not hear what you think is power.
Construction: Used with a stock header, this muffler has an aluminum canister with stainless steel internals, a mild steel midpipe and a Vortex quiet insert
Weight: Muffler only, 5.6 lb
Sound: 92.1 dbKTM 25O SX-F EvoX
Slip-on with Vortex Insert
Sound: 95.8 db
On the Trail: Quieting down the 250 SX-F is a big challenge. Big Gun’s system shows us it can be done; 95.8 decibels is not bad for a loud-natured bike. The pipe kept its quiet but left something to be desired out of the bottom third of the power spread. The already slow-on-bottom KTM powerplant suffered even more under the muffling of the Evo Vortex insert. Power delivery and transition from bottom up were improved over stock, with controllability and smoothness emphasized. This is a good pipe for fast off-road or wide-open desert situations. It’s likely that jetting would help the bottom.
WR450F Stainless SA Full SystemFit and Finish: Excellent alignment-you can tell it was designed by someone who works on bikes. The Dr. D has a very clean look and super sano installation with no excess anything. Our only issue is the header hangs low and looks vulnerable.
On the Trail: The Dr. D system received mixed reviews from our testers as a result of differing riding styles. Jimmy, who has a very smooth throttle hand and rides lower in the rpm, felt that it had good, smooth bottom like stock with more chuggability, then it effortlessly comes alive into the midrange, revving quickly or staying usable into a long pull on top. It shows a dual personality: great for trail riding and can come alive for a racer. This impression was backed up by Jesse and Derek, who use a bit more throttle and rev the bike a bit more. They thought this was a pipe that liked to explode with power instead of laying it down softly. It was a torquey pipe with serious low-end power that built to a ripping top-end but was very manageable when short-shifted with less throttle.
951/808-1114Construction: Two-piece system with stainless steel construction and aluminum canister with a quiet core insert
Weight: Full system, 6.9 lb
Sound: 93.0 db
WR450F Ti PowerCore Slip-onFit and Finish: The folks at FMF do their homework; this muffler has great installation and alignment. It has a distinguishing look with the anodized titanium finish. It is light but feels tough.On the Trail: This is another pipe that earns differing impressions with different riding style. For those smooth on the throttle, it was aggressive. It’s snappy on the bottom, where it isn’t so smooth, then in the mid it gets stronger, peppier and revs pretty quickly to the top, where it wants to be short-shifted. It didn’t feel like it had real torque on the bottom to prevent stalling. It is best for riders who ride higher in the rpm range like Jesse and Derek. They felt it had a smooth power progression with stronger mid than the stock unit and a good surge of top-end juice. Then it really came alive on top and produced a healthy, responsible sound. A favorite for boosting top-end with a good hit of power to let you know it’s working. It’s a great value for $299.99.
Construction: Titanium body with stainless tubing
Weight: Muffler only, 4.8 lb
Sound: 93.2 dbCRF250X
Sound: 89.4 db
On the Trail: Power was boosted everywhere, especially the bottom and mid. Smooth on top but overshadowed by snappy lower-rpm power. This pipe is meaty where the stock unit tends to lag.
WR450F Off-Road Series Full System
Sound: 99.5 db; non-compliant (see www.dirtrider.com)CRF25OX Off-Road Series Full System
Construction: Titanium canister with stainless pipe
Sound: 95.0 db
Fit and Finish: Mounting the Hindle system takes some setting up because of the numerous parts, springs and spacers, but it has good alignment and fit.
On the Trail: This pipe was much louder than the others on the bike-the sound carried much farther, too. The power felt flat everywhere until the top, where it surges and will pull right into the rev-limiter. There is more snap right off idle, and it builds smoothly but is lazy in response until it gets into the top. Power in the low-rpm range is similar to stock, but it is louder.
WR450F X3 Enduro Full SystemFit and Finish: The X3 took us 30 minutes to install with all the springs, bands and a tight fit at the header area. Once mounted, the quality is top-notch and fit is tight with complete hardware. The springs supplied were too short and stretched out. This one gets a B- for mounting but an A for quality.On the Trail: The X3 is snappy on the bottom and torquey all the way through the mid, where it is fast-revving. It easily pulls a gear high, but the power is not overbearing when revved out. In the upper-rpm range, it pulled really well in a long and usable surge with really strong power. The X3 is a favorite for improving the entire power range, yet that power keeps it smooth and controllable all while holding the tone down.
Construction: Titanium canister with stainless steel pipe
Weight: Full system, 7.0 lb
Sound: 93.1 dbKX450F X3 Motocross System with Quiet Insert
Construction: Titanium muffler body with titanium pipe and 96-decibel insert
Sound: 95.7 db
On the Trail: This system keeps all the snap of the stock setup but fills in the humps in the power delivery and makes it smoother overall. It still rips on top like the stock bike but is noticeably quieter. It would have rated very highly according to Jimmy on our recent motocross pipe comparison and is now a permanent fixture on his Long Haul KX450F.(Side note: We tried the exact same setup in a carbon-fiber can and the photo is the result. Typically carbon and sound-reducing inserts do not go well together. Leo Vince said it had a bad batch of cans and hasn’t seen this but once before on a streetbike application.)
WR450F Type 496 SA Slip-on
Fit and Finish: The 496 gets an A+ for mounting with its superb fit. It bolts right on-all holes line up perfectly-and it is as durable as anything we have tried.On the Trail: This is a full racer pipe, which is not the best option for the casual trail rider. It just barely passes sound and likes to rev and rev fast. It is light in the low-end compared to when it comes to life in the mid, then it really pulls into the top. The top is a little flat; it feels like it wants more gas or a bigger main jet, but the bike is happy spinning rpm.
Construction: Aluminum body with stainless steel pipe
Weight: Muffler only, 6.1 lb
Sound: 95.8 dbCRF250X Type
Sound: 92.8 db
On the Trail: The snappiest pipe we tried on the 250X, the 496 loves to work in the midrange. The bottom-end has good torque and snap, whereas the top goes a little flat and tells you to shift. It makes the bike more of a torquer while having a racy edge to it. It was a little loud.
WR450F Titanium Slip-on
Fit and Finish: Mounting was a little floppy with the band, and the hardware was not the right length, especially at the lower mount, so C- for mounting. Aside from the mounting and hardware difficulty, the muffler is nicely built.
On the Trail: The Scorpion gave the WR big bottom-end improvement. The mid and top work really well but are surely overshadowed by the big boost off the bottom. It isn’t overly powerful; it just works well down there. The power was broader than stock with some added torquey midrange goodness.
Contact: www.scorpion-exhausts.com; see your Parts Unlimited dealer
Construction: Stainless steel internals with titanium outer casing
Weight: Muffler only, 6.5 lb
Sound: 94.3 db
WR450F E2 Slip-on
Fit and Finish: The E2 bolts right up-no hassle or fuss-with great alignment and a simple design. The finish on this pipe is clean, with a strong industrial look. The square can is tough but can rub on the tire slightly as our test unit did.
On the Trail: This is a good pipe for riders who like chunky chug power. It likes to be ridden a gear high everywhere compared with stock. The E2 boosted power across the board, with the biggest improvement in lengthening the mid-to-top and adding some legs to the tranny. There is a meatier surge on the bottom, a similar mid to stock and a more usable top pull. It makes a good sound but is a little on the loud side for those worried about noise. A favorite for a utilitarian, durable pipe that gives you your money’s worth in performance enhancements.
Construction: One-piece aluminum can and stainless steel tubing
Weight: Muffler only, 6.3 lb
Sound: 95.4 db