A good blow off valve is an absolute necessity for high performance turbo systems. A well-engineered blow off valve prevents turbine damage by quickly relieving excess boost pressure without sacrificing boost response. A'PEX engineers have developed the Twin Chamber Blow Off Valve. The Twin Chamber Blow Off Valve is an adjustable, high-response unit for use on a wide range of applications. Rather than relying on the vacuum chamber alone, the Twin Chamber Blow Off Valve harnesses boost pressure in a second chamber to assist in opening the relief valve. This design allows the use of a unique flat-valve design, which provides excellent valve response under both low and high boost conditions without sacrificing flow capacity. Blow off sound can be adjusted by turning the red collar at the base of the unit. With its innovative design and adjustment features, the Twin Chamber Blow Off Valve is flexible enough for use on streetcars as well as racecars.