I tested my exhaust with a DB meter.. checked it at idle and 1500rpm.. with just the Dynomax muff it was 90db and 96db.. with the resonator and the Dynomax(res was before the muff) it was 86db and 93db with a much better note EDIT all readings from 3' away at the back of the car at work we did our noise readings from the side of the car 3' away.. we did drive by test also.. at different rpm and a WOT reading for the drive by