Greddy Revolution RS Exhaust 2011-2014 Subaru Impreza STI Sedan (single exit to right)The Revolution RS for the 2011 14 Subaru WRX STI sedan features full 3. 0 diameter piping, allowing a more free flowing exhaust which provides superior performance. Greddy dyno testing has shown an increase of 12hp, and an amazing 32ft lbs of torque! Engineers designed this exhaust system as a single sided cat back layout with minimal bends. The resulting benefit is a cost effective, light weight system that improves flow and performance. Classic