So I am trying to decide whether to go with a full catless downpipe with elbow like the Tork, or with just the straight section that retains the factory elbow. This thread has been done a million times there are good arguments on both sides and it always turns into a heated debate. Meet other stamp collectors interested in Argentina stamps. BOV is the common and incorrect term that lumps true blow off valves and bypass valves under the same term. The BOV is a lot louder and sounds like a burst of air, the BPV is a little louder than the stock unit but sounds generally the same. Motor mounts, motor torque dampers, throttle. Some older turbo'd cars didnt have BOV's. Each valve is made of durable cast and billet aluminum frame and the valve to diaphragm ratio provides performance that cheap piston types cannot offer.