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.
2011.5 SG E92 ///M3 6MT | CF kidney grills | IND SG painted side grills w/ tinted lenses | Painted bumper reflectors | TMS 90mm stud kit | Rear fog light mod | Active Autowerke exhaust |