Stage X Tumbler Generator Valve (TGV) Thermal Delete Kit

Tumbler Generator Valves (TGV) are fitted to Impreza WRX, Forester Turbo and Legacy GT models from 2001 onward.

Their main purpose is to reduce emissions from a cold idle in order to meet EU emissions regulations (similar regulations exist in the US and Japan). This does little for performance, and it is not uncommon for the sensors and motors connected to the TGV body to fail, leading to limp mode, check engine lights and considerable expense in replacement parts and code clearing.

The standard TGVs work like a throttle body, with twin butterfly valves in each tumbler housing to control airflow. Even fully open, they restrict the air entering the cylinder head ports and reduce performance.

This Stage X TGV delete has no butterfly valves, sensors or motors, and gives a smooth, direct flow of air into the cylinder heads. The ECU mapping must be adjusted initially to prevent a check engine light. The result is increased performance, improved reliability and a much better appearance, thanks to the crinkle black or red coated finish.

Thermal kit

• Heat spacers help prevent heat from conducting from the cylinder head into the alloy inlet manifold. The cooler, denser air aids performance and keeps temperatures stable during prolonged running.
• Replacement bolt kit: the spacers increase the manifold height, so the longer bolts maintain the OE thread depth in the cylinder heads and keep the manifold and TGV housing secure.
• All necessary manifold gaskets for a trouble-free installation.