Chris had a chipped 7.3 in his old F250 and that would pull all day long like a train. Plus, pulling the very same car hauler with Pearl on it, he would get 21mpg while the best I could do with my 6-liter power-stroke was maybe 17.5 - down hill, all the way from Massachusetts to South Carolina. After a while, I just stopped looking at that gauge and flipped it to the turbo boost gauge, instead - that was more fun to watch.