I should amend my post a bit. The day I had this done I brought it straight home from the muffler shop and parked it and went to work for two days. It definitely did not make as drastic a difference and both I and the very experienced, over 23 years with his own shop, muffler technician thought it would. However, I took it out and experimented with it quite a bit last night. The cold start if definitely sounds louder for that first 15 seconds or whatever it is. Accelerating from a stop it feels more powerful but isn't too much louder. It you hammer on the accelerator while in motions say at 40 mph or so you can really notice it. It also, "seems" more responsive. As far as backfires are concerned. I could not no matter how I tried get it to backfire. Maybe the X pipe eliminates this characteristic I don't know.