My Magnaflow 2.5" X-pipe with cats and catback are quieter than Flowmaster 3 chambers without the drone and way quieter than Flowmaster 2 chambers. I got to try 2 chambers for free...they put 2 instead of 3 chambers on the first time with stock 2.25" system. The 2 chambers would give me a headache and the 3 chambers were better but had bad drone at about 2k rpm.
Don
Don