I had this installed at ACM about a month ago and I have zero complaints. It's loud when I want to enjoy the sound and quiet enough to not bother me at other times. Drone is definitely subjective. I would say drone is minimal, so little that when I was on conference calls for almost two hours while driving between 60 and 75, no one noticed until I deliberately went WOT at the end of a call. If I had to guess, I would say ACM does this mod with no exhaust leaks and that's why drone is not an issue. Jay has done over a hundred of these and it shows in the quality of the cuts/welds.
Ian 2009 e90 MT