First off this is my first post, but I want to thank everyone for the great info I've already gotten from here. I have a 2007 Silverado 4x4 new body style crew cab with 5.3 engine and auto tranny. I ordered the Superchips Flashpaq and it should be here early next week. I've put a leveling kit on and am running 285/70R17 tires. I'm wanting to gain some mileage back. It dropped from right at 14mpg to 12mpg after changing tires. My question is, what program should I run? Should I run the economy program, and will there be any performance gains with this setting? Or should I run the performance setting, and will this help my MPG at all. I will probably add a Volant CAI next, but not for a few months.