I have a lb7 duramax with a 4 to 5 inch straight pipe. It was ungodly loud especially on the interstate. This muffler doesn't make to much difference at low rpm (which it still quiets it down a bit) but it makes a world of difference once you give it throttle. Especially at 2k rpm when it starts to drone out. The truck still sounds awesome but not nearly as loud! It was exactly what I wanted!!
MBRP Mild Tone Muffler GMC Sierra 2010
After tons of research on forums, auto aftermarket sites, and even calling the manufacture directly; I finally decided on the mild tone muffler (I couldn't find any reviews on this model). I have to say I am very satisfied with my decision. The sound is noticeable but not overbearing at all. Nice deep tone. Love the straight through design. I feel that it improved performance with a 3" cat back. Highly recommend.