Ive never heard of anybody stacking tuners on a gas motor. but then again im a diesel guy.
Your mileage is most likely suffering due to you lift and large tires. when you lift a truck that big you have to accept the poor mileage. I fee your pain. I have a 6" lift and 35s and i only get about 12 in town.
Hey Jason, I own a 2007 Dodge 2500 Hemi 5.7L and have recently added 37" Cooper SST MT's and a 6" suspension lift. The truck drives great but even with my Bully Dog Programmer, it says I'm getting about 6-7 MPG. I'm wondering if I can add a chip on top of the programmer for better fuel economy. Or if anyone already has a bully dog programmer to help me get the best MPG out of it.