I have been running this exhaust for little over 2 weeks now and like @
mengmoua said, it is louder than I thought. It has a really deep and bassy tone. It is a bit loud inside the car between 2.5k and 3.5k rpm (at least for me) but not that bad. I can still have a good conversation with my wife inside the car with the radio on when cruising on a highway.
I'd say in my honest opinion the MXP Comp RS is somewhere between an N1 and the Q300 when it comes to loudness. It will definitely be louder with a header.
Very well constructed exhaust.