Skip any hand held "canned" tuners by the big names like Edge, Bully dog, diablo etc. Check out Black bear performance, they do great custom tunes. They also did a dyno test of the popular CAI's and the Air Aid JR MIT kit came out with the most HP and TQ gains.
Being in STL you probably have somebody local to you that can custom tune LS engines.... like Blackbear does. That will net you the best MPG and much more HP/TQ than any hand held unit will be able to offer to you, and usually at a better price. Plus with tow/haul mode they can play with the shift points if you wish to be more performance driven or if you do really use it to tow with they can improve it.
Also I would make sure to have them turn AFM OFF. As well as take the torque management off or at least bring it down so it doesnt limit as much. Nor can warranty be denied for tunes, unless your tune sucks and that is what caused the problem. They MUST prove what caused the problem to void warranty work. But if you do take it in for warranty work there is a good chance they'll wipe your tune off the ECM... why lots of guys have a spare ECM that they tune and keep on with the factory tune on it... they never run into any problems with warranty or having their tune erased.
NRA and DU member, are you? if not you should be!
rabbitdundied wrote: I use my mojos in places I don't want birds to land.