This BOV offers adjustable sound and quick response. Two chambered body using an assisting vacuum hose. This unit incorporates a revolutionary design in boost pressure release systems. Blow off valves allow built up boost pressures to escape into the atmosphere when the engine is no longer under load. This prevents the pressure from backing up into the turbine compressor housing, causing It to stop, and causing potentially destructive damage to the turbo. The BOV is also adjustable to allow desired amounts of boost response between shifts. Unlike conventional single chambered blow off valves, the twin chamber blow off valve uses two separate chambers with an assisting pressure hose. This design allows for a short and highly sensitive spring in the first chamber that controls a piston and a valve in the secondary chamber. The result quicker valve response under low AND high boost pressures. The blow off valve also gives the user the ability to adjust the blow off sound. By turning a disk near the base of the unit, the exhaust fast release volume can be adjusted to normal, loud, and extra loud