The OEM tumble generator valves (TGV) found on the Subaru EJ engines create an air flow restriction when it comes time for performance upgrades. Their prime purpose is to reduce emissions from cold idle to meet standards governed by the EU emissions regulations. The Aeroflow TGV Delete's do not contain any butterfly valves, sensors or motors. Allowing a direct flow of air into the cylinder heads with no restriction. It will be required to adjust the ECU mapping to take full advantage of this modification. Manufactured and CNC machined form billet aluminium and anodized stealth black. They provide additional clearance for larger turbo inlet pipes. Designed to with factory or aftermarket top feed fuel injector rails.