VIDEO: FMF S/S Aluminum Factory 4.1 Muffler System Review - DR Tested

The 2016 YZ450F was Dirt Rider's open class motocross shootout winner, but that doesn't mean it can't benefit from a little engine massaging. Kris Keefer decided to to try an FMF S/S Aluminum 4.1 muffler system to see if it improved the already potent engine package the Yamaha has to offer. FMF's aluminum 4.1 version still incorporates a carbon fiber end cap and comes with a spark arrestor screen for all you off-roaders out there. The complete system system will cost you $799.99 and is made right here in the good ol' USA!