BOV Supersonic Black from Turbosmart Blow Off Valve Supersonic Black Supersonic A full atmospheric BOV for racers and serious enthusiasts who want to be noticed. Supersonic provides a superior flow performance with the famous "supersonic” sound. Featuring a tool-free adjustment via a rotating cap and a positive-seal piston this is Turbosmart loudest BOV. Color: Black Supplied with: Quick-Release V-Band clamp, Yellow Spring (rated -22 to -20 InHg) installed, and 38mm weld flange.