FMF Racing Powerbomb Stainless Header for Yamaha YFZ450 04-09 & 12-15/YZ450F/WR450F 03-06FMF 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