I love my TAG. Noticed about 1 - 1. 5 mpg under a load, minimal empty. Definetly spins up faster and just seems to pull better at lower rpms. Dynoed it at Imler Diesel in Sacramento on his load dyno and showed no difference, up or down. All in all, I'd put one in another truck if I could. Love it!!
FYI - Drove from Gilroy, CA to Duncan, OK to Sacramento, CA with a homemade plywood camper shell. Went to Fall Classic to pick up pigs. On return run had about 2000# of pork in the back along with all our crap. Whole trip, cruise set at 80, got 18 mpg to Ok, 16. 5 back to CA. Love my TAG and Aeroturbine!