FYI I have 15k on my 7.3 tremor, with 4:30 gears, 35 inch tires, a stock 2 inch lift (17 to19 super duty suspension), all are stock components that come on the tremor package with the cut air damn I am setting 14 mpg on the highway. I don’t think this is bad considering what it is, if you want better a standard super duty with 3:55 gears will do about 2 mpg better.
I’ve owned allot of trucks, the only one I ever get complements on is the tremor, everyone seams to like it and to be honest I’m very satisfied espically with the 7.3.