Question: what are tgv on subaru?
Answer: Tumbler Generator Valves (or "TGV" as they are most commonly referred to) can be found on Impreza WRX, Forester Turbo and Legacy GT models from 2001 onward. ... The standard TGV's are similar to the design of your throttle body, encompassing twin "butterfly" valves in each tumbler housing to control air flow.