I have Active Autowerke with stock x-pipe. It is a decent amount louder than stock, it has more of the unique muscle V8/German exotic high pitch to it. My friend could hear me before she saw me when I was driving into her neighborhood today. I wouldn't say it was LOUD though.
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