I have mentioned before that I have a Hypertek Programer in my 2001 7.3. The Hypertek has 3 settings with 3 giving the most power. I always run the truck in #2 and the increased power is great. I don't push the truck and try to take care of it because as has been mentioned, the tranny is the weak link. My truck has roughly 125,000 miles with the original transmission and there is no indication of a problem. My thoughts are if you try to take care of the truck, you won't have any more problems with a tuner installed. I have had mine 4 years.