I think 2x4 or 4x4 platform will change your expectations.
I have a 2002 F350 SuperCab PSD with a 7.3L, Heavy mods to much to list, ie. upgraded Tranny W/TC, 70Hp Inj, 4'TurboBack,Chip,K&N,
ETC.etc.:burnout
I get 40MPG at 2000RPM at 70MPH on Cruise Control.
The only mod that would effect the OEM computer would be 20x10"s with Cooper ZEON XST Street Tires 305/50/20"s on a 2x4 drivetrain.
Just thought I would loose theese #'s with the high flow inj, But The truck still does great on cc. BUT Around Town My RIGHT Foot is dropping my fuel needle faster, but that's directly assoc w/ the SMILE
on my FACE.
Good Luck, I Think an Intake w/ a 4" Turbo back then maybe a chip and some gauges should suit your needs if done in that order. C-Ya