Active Autowerke M2C Equal Length Mid Pipe includes Active F-braceWE ARE RECOMMENDING TO OWNERS OF CARS WITH AFTER MARKET DOWNPIPES TO USE THE RESONATED VERSION BUT WE HAVE ONLY TESTED WITH THE STOCK REAR EXHAUST AND ACTIVE VALVED EXHAUST. ON THE M2C WITH STOCK EXHAUST, THERE MAY BE SOME RASP. WITH STOCK DOWNPIPES, THERE IS MINIMAL RASP so you may also want to opt for the RESONATED VERSION. HOWEVER IF YOU HAVE THE MPE OR CS EXHAUST, YOU SHOULD CONSIDER USING THE RESONATED VERSION. WE DO NOT GUARANTEE RESULTS WITH