FMF YAM YZ/WR450F'03-06/YFZ450'04-15 S/S PWRBMB HDRThe redesigned PowerBomb is a four stroke header that incorporates FMFs patented PowerBomb module at a precise location in the initial stage of the header. By positioning this Bomb at a key point in the system, increased performance and flow is achieved through the expansion and contraction of exhaust sonics through the system. Result is a flow increase of nearly 10%! The outer chamber in the Powerbomb allows the air to expand, cool and ramp back up