201 miles/ 10.7 gallons to refuel since last= 18.7 miles per gallon.

hell...not bad but i know it gets about 2-3 better w/ PURE highway.
the 18.7 was mixed driving so i can't complain.

i do have a couple tricks to increase by 2-3 maybe 3-4 if lucky...
1. I'm looking for a good shell that flows w/ the cab to reduce drag.
2. Good tune-up & regular maint.
3. Might consider a low, low boost turbo eg. 1-2 lbs max.
4. Driving habits...eg.hypermiling...lol...j/k

edit: OUR rigs are virtually the same setup!

 

18.8 on my last tank coming from georgia to florida going between 75 and 85 for the majority of the time on I95.

 

12-13mpg--84 4x4, 9"lift, 35"mudders, 4.10gears