This flow control valve provides improved throttle response and much quicker starts by drying out your waterbox at low rpm and idle speeds. Tests have shown an average acceleration improvement of 10 feet over a non-equipped model in the first 50 feet. The flow control valve allows unrestricted water flow to the stinger for better top speed, yet controls the amount of water at low speeds for better response. It also allows for an easier tuning of the carburetors. The flow control valve will not interfere with normal engine or exhaust pipe cooling and is compatible with all electronic water injection systems. This model is preset at 3.5 p.s.i. and is adjusted by adding the supplied stainless steel shims to increase the spring tension. Fits all watercraft with OEM or aftermarket exhaust systems (e.g. Factory Pipe) except Yamahas with OEM exhaust.