FMF Racing Powerbomb Stainless Header for Yamaha YZ250F 07-09FMF PowerBomb Header Yamaha YZ250F 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