The Kompact series of Blow off Valves are designed to be direct replacements for VW/ Audi Bosch-style bypass valves. The Kompact Dual Port allows a portion of the charge to be bypassed into the intake system, keeping the car's ECU happy and the engine light off, while the rest gets released through the horn on the opposite side. Each of the models fit in all the same applications as the original bypass valve, and can also be used in universal scratch build kits.