Well today I dun it. I had my 2004.5 LLY w/Attitude MBRP'ed. The install went easily. One pipe to cut to length and one hanger that needed bending. Other than that the install was flawless and took approx an hour and 10 minutes.
When it was all done, I was pleasantly surprised to hear an exhaust that was NOT LOUD. It was slightly throatier, and a touch more turbo whistle, but other than that quite pleasant to NOT have to turn up the radio to hear it. No reasonance in the cab either.
Seat of the pants with the Edge on setting 1 the truck is livlier and more responsive. Time will tell, but I am pleased with the fit, finish sound and look of the system. The 5" tip looks bad too!! 
2004.5 2500HD Extended Cab, Loaded, LineX, Duramax LLY, Allison, Juiced with Attitude, MBRP Stainless with 5" Stainless tip, Banks Cold Air Intake & Air filer, EGR blocker with finger stick, Front bypass pipe. Towing a 2006 33' KZ Durango 5th Wheel
