Guys, try different settings.
Tow tune is built for heavy towing and not for the best mileage. Things like turbo brakes and more boost hurt mileage in the tow tunes.
Every truck is different and will react differently to tuning. Things like tire size, intakes, driving style help or hurt mileage.
The biggest problem I see when a customer calls and is having mileage problems is there is an aftermarket air intake on the truck. When they install the factory one, mileage pops up at least 1.5MPG.
Also winter fuel is a huge factor, if comparing winter fuel#'s against non-winter fuel#'s there will be a big difference.
Lastly if you are not seeing the results you feel you should after testing the different settings, drop me an email with results and findings. What works for 100's of trucks, may not be working for your set-up. I'll make some changes and we'll try again.