[wantabe351]

Ok heres the story-05 CTD Dually, auto, 4.10 gears,BHAF,36" Magnaflow muffler,Edge/Attit. set towing#2,air pressure set at 72 psi all tires- driving most of the time at 68 to 72 mph and the outside temp at 72* to 82* so ac was on. Now my camper, a 5er, is like a big brick (12'4" tall)..I think 10/11 mpg would be ok but 8mpg is low,also my boost guage read about 18 to 20# of boost driving most of the time.We traveled on I80 to I90. This is hand calculating my mileage...Maybe I need a GV unit to drop my RPM down to about 1700 rpm instead of 2200 rpm....What do you get towing 20000# to 24000# w/4:10 gears running 70 mph? I know I should drive at 60mph, but in SD 75mph speed limt and most other states were 65 to 70 mph...