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!
Congrats on getting the LBZ. Towing on the flats I get around 11-12 mpg (no jackrabbit starts). Towing up into the High Sierra it drops to 8-9 mpg, there are a lot of steep grades. I start out at 35' ASL and tow to 6500' ASL. Sure is nice maintaining posted speed limit when towing in the hills.