It sounds smooth on my 2015 ATS, not exactly loud until you buy the down pipe but it’s definitely better than stock

This is just one of the many ZZP mods on my car, CAI, Intercooler, down-pipe with high flow cat, 7163 turbo, cams, rods, valves. The exhaust fit perfectly on my ATS sedan. There is a noticeable sound in the cabin, but I wanted that. The exhaust has checked all the boxes for my car.

Installation was a breeze. Take off the stock exhaust and install from the muffler forward is how I did it. Quality and material seam very good. Fitment of the piping is near perfect and fits nicely against the car. My only issue is the driver side exhaust tip sits about 3/8" LOW. Ill need to modify the stock mount to bring it up. would be 5 star otherwise.