No I double checked them, the stock computer has about a 1-2 mpg flaw. Now I have heard of some two wheel drive trucks getting better than me on the highway but I do real good in the city from what I hear. I do have the 410 gears and keep my rear tires at 75-80 psi because I tow alot of weight, when I kept them down around 50 psi I loose almost 2 mpg. I have also noticed that it makes a differance on where I get fuel the East coast station near my house I get the best from, Texaco and Chevron are the worst for me. I was going to sell it but not for one more year I want the 6.0 to have one more year under it's belt. Have you heard anything about the airaid TB spacer I have one but havn't put it in yet, they say better low end and maybe 1 mpg.
My brother just got a 03 with the 7.3 bone stock 1500miles he is getting 17.5 over all, it's a 250 long bed crew cab 4x4 so we'll see how it get's he's going to do some stuff to it but he doesn't tow just tools in the bed.