Greddy Type R Blow Off Valve is made of durable cast and billet aluminum frame and the valve to diaphragm ratio provides performance that cannot be found in a cheap piston type blow-off valves. It is easily adjusted to prevent both premature boost leakage and compressor surge. The spring stiffness adjustment screw gives users the option to match vehicles with mild upgrades to heavily tuned engines. Very high quality unit that performs very well. Many people regard this BOV as the best BOV to use for high performance engine, capable of handling over 375HP!