Dirt Bike Reviews - FMF 2004 Honda CRF450R Factory4 Exhaust System - From Dirtbike Experts at Dirt Rider Magazine

Although the '04 Honda CRF450R comes straight off the showroom floor ready to race, the crew at FMF have put their R&D; time to good use on the bike. In stock trim, the CRF has good, solid power delivery but tends to hit the rev-limiter too quickly. The Factory4 system uses a new Power Bomb header pipe along with a new oval-to-round canister. It moves the weight of the bike a tad forward and is 2.8 pounds lighter than the stock system. The biggest difference with the new FMF Factory4 is on the track. Bottom-end power is more responsive and transfers into a hard-hitting midrange. The midrange power carries much longer than with the stock exhaust system, making the bike easier to ride. Top-end power pulls strongly and for a longer period of time before hitting the rev-limiter.We tested the Factory4 on several different types of tracks, and overall, the bike's characteristics are much better with the FMF system. No jetting changes were needed during our test, and we didn't experience any unusual misses; throttle response was instantaneous and very predictable. Depending on riding style, we noticed a bit of wear on the right side of some of our tester's boots from the Power Bomb's chamber, which sticks out farther than the stock header. FMF makes a trick shield that is sold separately to prevent any damage to your right boot. The Factory4 system installs easily and retails for $699.99.DR Tested: 9.5FMF Racing: 310/631-4363; www.fmfracing.com