here is our exp running Fords coast to coast and this is like leaving here in NC anywheres from noon to 4:00 in afternoon and would be in Tuscon around 9:00 pm on Sunday so we run the wheels off 7.3 and 6.0's and then load 2-3 trucks + parts back,, 1st thing if you can get by in your state remove cat, put 4" downspout with exhaust and will improve power and fuel mileage,, Both the 7.3 and 6.0 we gained from here to Tucson 50 gallons of diesel and here is another thing, when these trucks where new we found always a film on inside of windshield until the cat was taken off and it went away,, I went to doctor few years back and the dco asked whem I started smolking and said never,, reason a spot on my lungs which has went away and blamed that on these trucks, ++ we had a Ford Rep tell me to get rid of cat But remember save all those parts in case of trade in, Now for the final thought, In our business as far as working I might be the only one that will say this is that the Stock <except for exhaust coversions> 6.0 will out work, out pull any stock 7.3 < except for exhaust conversions> + thats also the cummins or duramax's as well thats loaded pound for pound, 8' beds stading straight up and all other wind obstructions and pulling hills up Flagstaf, Rockies or any other pull,, like I said I might be the only one that says that but for 13 years we did it ,, Now I have a 6.7 Cummins in our Ford and very happy especillay when we every trip is in the range of 35,000 to 41,000 lbs,, anyway my
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input oh one other thing if owning a 6.0 I would put the extended warranty to 200,000 miles < if still available >on it will pay for itself when going through injectors, engines etc...