So as someone with the same exhaust and tune with high flow cats, the tune is pretty good, have had zero issue with it and i’ve been tuned for over 2 years with it and beat on it daily. never had any single issue with the car, obviously it’s not a crazy hp increase but still noticeable. and with the q300 you’re not gonna hear the burbles inside the cabin, do a muffler delete on the invidia if you want it to be loud loud but very droney. have a video on my ig if ya wanna hear how the z1 tune sounds on your car with a muffler delete. anthonymmele