The Racing Bypass Valve Type 25 was
specifically designed to replace the 1 inch (25mm) Bosch Bypass Valve used in
most Volkswagen and Audi applications. The Bosch valve is prone to failure in
stock application and not adequate for holding boost in "chipped" 1.8T equipped
vehicles. The RBV-25 spring tension is adjustable, making it ideal for your
modified vehicle. The RBV-25 relieves the pressure surge caused by changing
gears or backing off the throttle quickly.