Alloy Recirculating Ram Dump Valve Fitment Guide Evo 4 Evo 5 Evo 6 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. Unlike the Diaphragms valves this uses a single piston single spring to prevent the valve from leaking air into the intake system at idle. This prevents our diverter valves suffering any of the failures associated with single piston and diaphragm type diverter valves.