BOV boost pressure relief valve AMAZING SOUND EFFECT !!! Protects your turbo !!! The standard 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: Outer diameter of the inlet: 25mm. BOV boost pressure relief valve AWESOME 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 by the way it produces an amazing sound effect - characteristic PSSSSSTT !!!! High quality workmanship Dimensions: Outer diameter of the entrance: 25mm