I have a 2003 2500HD Chevy with the Duramax & Allison. So far am very happy with it. I have only added the Hypertech power unit and of course set it to the 90 HP setting. I often pull an enclosed trailer grossing around 9-10,000 lbs. But without an EGT guage I know I'm in for trouble if I keep pulling this type of load. I'm hoping to learn what are the better improvements for the dollar while not losing reliability and economy.