I have the 06 2500 Quad cab 4x4, 5 speed auto with 5.9 Cummins and love it. This is my second Dodge Cummins. I put an after market cold air intake on along with a 5 inch cat back exhaust and the EDGE Mileage max chip. At 65 MPH I am getting a WHOPPING 28 MPG highway and 19.1 city according to the overhead computer and also against actual mileage according to speedo. Dealership has no problem and says they actually recommend the Edge Mileage Max chip which does not affect the warranty. I wouldn't have any other set up as the increased mileage and HP is amazing. Wouldn't have it any other way.
Overall strength of the engine & transmission set up. Just a super truck all around.
Some kind of bumper strip along sides of truck to stop dings from other cars. The one included by factory is to low.