Gas mileage on a new 8.1

Yep, the power was the reason I changed to the 8.1L from the 6.0L. I knew the MPGs were going to fall off, but that is the trade for POWER!!! I was near the top end of the towing range of the 6.0L and while it did the work, using the air forced me to stay in 3rd gear and I could never use cruise as I had to anticipate inclines and work the throttle ahead of time. Cruise liked to wait and then jump back to third to much. Working the throttle I could keep in OD most of the time without much jumping unless the terrain kept changing by large margins.