If the drone is the issue, I've heard RPi's exhaust drones like crazy. I love my Active Autowerke exhaust. Very unique low growl/high pitch exotic sound and barely any drone!
2015 AB/SO F80 M3 6MT | 19" Black M437 | AutoTechnik Black Front Grills | BMW Performance Side Grills | Painted Front Bumper Reflectors | Gloss Black Exhaust Tips
GONE 2011 SG/Blk E92 M3 CS 6MT