GV delete intake manifold risers. American Legacy GT models come with TGV (Tumble Generator Valves) to improve start-up emissions. However, they cut available air flow through the intake manifold by up to 50%, reducing overall efficiency, and reducing the amount of air larger turbo upgrades can flow through the system. These are from the JDM Legacy GT, which did not come with TGV's.Price is for a set of 2. The TGV's suit a side feed style injector.