Why not be the first to try an OEM Exhaust Mod (non-perforated). Costs about $300-400. It was the best money I ever spent on a car (for my 2013 M3) and I love the way it sounds every time I drive it. Also ridiculously cheap compared to most catback options...
If you can't bear to wait the 3-6 months then you can get this done in a couple of hours!
