I loved my 6.7 for the first 5k, it was very strong and got good MPG and had no problems. Then on may way to work one morning my yellow light of death started blinking and the truck died. It was towed to the dealer and the turbo charger was all burned up inside, it looked like it had over a million miles on it, and when they looked further the valves were burnt and full of soot, and my pistons were shot. On a conference call with Cummins and Dodge engineers they did admit that they are having what they called "back pressure issues with with new emission system." I never beat on my truck, used only ultralow sulfur fuel, and never let it idle. The truck needed a complete overhaul at 5k. The dealer did an even swap with me for a 2007 5.9 last night. The 6.7 is an extremely powerful engine, but they really need to get the bugs out of the emissions and their "back pressure" problems. Good luck and I hope this helps.
2007 Dodge 2500 4X4 5.9L Cummins with 4 speed Auto, Quad Cab SLT Thunder Road with Jake Brake, 5" turbo back Cat Delete FBD exhaust, Edge with Attitude, 2"HBS leveling kit and Tekonsha P3 brake control.