I haven't had a chance to calculate my mileage yet, doing a bunch of other things with the truck right now that directly affect mileage.
Call Doug at Bamachips, he's really helpful and can guide you to the tunes that would be best for your type of driving. He can also answer any other questions about possible gains in mileage, torque, performance, etc. Don't worry, he won't try to strong arm you into buying one of his tuners. He's a really great guy.