All I can say is HOLY CRAP! Coming from a 2000 6.0 vortex this set up is awsome! The truck doesn't even flinch! 70 and sunny about 70 miles from home and 12.2 MPG--NICE! I am grinning!
I get 8-9 pulling a 14000lb cardinal. 16-17 pulling dry. I've always been fascinated by RV's and their gas mileage. I've heard of some getting 26mpg with theirs. Great, wish I got that, BUT not in this life time. I can safely say mine will get 21pmg on flat ground, driving 40mph.