I bought these for my 2013 Infiniti G37 sedan to use with Stillen Gen 3 CAI, Stillen HFC and a Stillen Cat Back exhaust system. When I introduced the high-flow cats, there was a slight rattle and buzz in the system. The addition of these resonators resulted in the elimination of ALL the rasp and drone. I can't stress enough how well they worked and would recommend them to anyone looking to ditch a rasp and/or drone.