[Fixjet]

My LBZ gets around 13 mpg towing a 7000 lbs. snowmobile enclosed trailer and 12-13 with the Laredo at around 8000 lbs. Running Duramaxtuners Stock Trans tunes with the DPS5 switch. 5 tunes, Stock, Heavy Tow, Light Tow, Performance Economy, and Race. Stock HP, 60,80,100, and 130. The truck runs much smoother with the tunes and gets 19-21 mpg empty highway and 16 around town on the 100 hp setting. The 2 tow tunes also include a turbo brake when your in Tow/Haul mode. Nice setup, spendy but very nice.