Replace the failure-prone, plastic factory diverter valve! Unlike the OEM Bosch diverter, this Forge valve is heat resistant, and holds more boost!! Made from billet aluminium, this recirculating diverter valve dumps the charge-air back into the air intake system keeping external noise to a minimum. This increases both quicker throttle response and higher clamping load to maintain boost pressure more reliably. Includes valve spring tuning kit - green spring (5-15 psi) is pre-installed, yellow (15-23 psi) and blue (23-30 psi) spring included in box.