I bought this Super 10 Si/Do muffler to replace the Super 40 that was on my 2012 GMC 2500 6.0L when I bought it. I like the sound of the Super 40 but it's not loud enough. Got this guy in the mail today and welded it on with no problems. To my surprise, the noise wasn't much louder, but it sounded better. I had one like this on my last truck and I remember it made such a big difference, I wonder what's going on? Anyway, great fit and finish, great price just not as loud as I like!