The factory BPV (bypass valve) has a couple of key shortcomings in construction and operation. First of all, tuned engines running high boost also produce a lot of heat in the charge air. Because the BPV is situated right on the compressor, it is subjected to the hottest part of the intake charge, and the heat from the compressor cover itself. This can cause the factory diaphragm to rupture, and if that happens and goes undetected for a while, it can cause damage to the turbo, as the ECU will try to compensate for the lost boost pressure by increasing turbo speed. Second, the operation of the factory BPV is not aimed at throttle response. Because of the soft spring and the solenoid valve that is in-line with the vacuum hose, it can only operate in two states ? fully open, or fully shut.