BOV boost pressure relief valve AMAZING SOUND EFFECT !!! It protects your turbo !!! Fully vented valve to the atmosphere or to the gear (DV). Continuously adjustable. Thanks to a strong spring, it can withstand boost pressures up to 2.0 BAR, making it perfect for cars with both diesel and petrol engines. The valve is suitable for vehicles equipped with a meter. Thanks to the partial return of air to the system, it will not cause computer errors and problems with "overflow" of the engine during gear changes. 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 workmanship. & Nbsp