I had the RR xpipe paired with stock. Sounded okay at half throttle, sounded raspy and like a trumpet at WOT. I didn't like the quality of sound much but a big plus is there's no drone.
2009 E92 M3 | Alpine White | Black Extended | Advan RS | Turner Test Pipes | Dinan Axle-Back | OETuning | Eibach Springs | UUC SSK | VRS Front Lip | VRS Type I Diffuser | Matte Black | RPi Scoops | MS Filter | Yokohama AD08 | F1 Pinnacle
Special Thanks: Gintani | OETuning | eAs