Congrats on the purchase, and welcome to the forum!
First up, JET is a JOKE. They do very little, can't compensate for tire and gearing changes, and are not worth the time to look at them.
Superchips makes a great tuner- does a little for power and fuel economy, but lets you adjust fan turn-on temp (great for when you're in deep water so you can turn them off as to not break one), gear ratio (compensate for changes), tire size (same deal), t-case gearing, and several other bits. It'll run ~$325 shipped from truckcustomizers.com (call and talk to Tom- tell him Mark from NY sent you- he'll hook you up), and is well worth it.
Last but not least, CORRECT gearing for the tire size you run can either increase fuel economy, and/or improve performance in terms of acceleration as well. Sometimes you get both, sometimes one or the other. Quadratec's knowledge center has a great chart as for gearing vs. RPM at speed with various tire sizes- check it out. Gear based on what you plan to do- not necessarily what you have now. If you plan to upgrade in a year or two from OEM 32's to 37's, don't re-gear now, however. 5.13's on 32's will make life suck
Anyway, welcome again, and fire away with some questions- Mark W.