Allows replacement of stock reed stop with a Rev-Plate which permits the reeds to open freely and function efficientlyThe top reed is lightweight and resilient for crisp throttle response at partial throttle or low RPMsThe stiffer, bottom reed is ported to provide maximum flow and horsepower at higher RPMsDual-stage design incorporates a specially shaped top reed and a ported bottom reedIncreases horsepower for less money