FMF PowerBomb Header Yamaha YZ450F / WR450F If you spend most of your time riding in the mid to upper RPM range the FMF PowerBomb is the header for you. The PowerBomb incorporates a patented chamber at a precise location in the initial stage of the header. This chamber allows exhaust gases to expand and then contract, resulting in nearly a 10% flow increase. Not only does the PowerBomb offer more usable mid to top end power, it also acts as a pre-muffler and can help lower exhaust sound output. Features: MX version focused on increasing mid to top end output from stock motor Reduces sound output Compatible with FMF mufflers only 100% made in the USA Weight: Stainless Steel 1.5 lbs