Haven't gotten my car Dyno'ed for true results but I didn't feel any different. Everyone has their opinion but I rally love the mod. I had a Magnaflow axle back exhaust before I did the mod. Magnaflow claimed an + in HP and lightweight but I couldn't take the drone anymore. So I sold my Magnaflow and bought a spare OEM exhaust, did the mod and still had $400 extra in my pocket. I really love the sound and the best part is when your cruising it's quiet but once you start adding throttle it really comes alive. I have gotten more compliments with the OEM Mod then when I had my Magnaflow.
BMC filter, OEM Exh Mod, ESS Direct Flash tune, flat black kidney grills, color painted front reflectors, LUX Angel eyes, -2012 SVT Raptor 4 dr -09 E90 M3