BOV boost pressure relief valve AMAZING SOUND EFFECT !!! It protects your turbo !!! The serial DV valve forces the air into the circulation, while the Blow Off valve - the atmospheric valve lets the air out, which protects your turbo, and at the same time produces an amazing sound effect - characteristic PSSSSSTT !!!! High quality. Dimensions: Inner diameter of the inlet: 35mm Outer diameter of the inlet (spigot): 45mm Inner diameter of the outlet: 28mm Outer diameter of the vacuum nozzle: 5mm BOV boost pressure relief valve AMAZING SOUND EFFECT !!! Protects your turbo !!! The serial DV valve forces the air into the circulation, while the Blow Off valve - the atmospheric valve lets the air out, which protects your turbo, and at the same time produces an amazing sound effect - characteristic PSSSSSTT !!!! 35mm Outer diameter of inlet: 45mm Inner diameter of outlet: 28mm Outer diameter of vacuum port: 5mm