I am thinking about doing some aftermarket performance upgrades to my truck. I have a 2009 Chevy Silverado 1500 with the 4.8L. Not crazy just bolt on stuff. I want to do a cold air intake as well as a full exhaust system including a high flow cat. I will also be re-gearing the rear differential from 3.23 (suck) to 3.73. My understanding is if you start swapping things a custom tune is needed to take full advantage of the new parts. I have also been told that you can easily lean out your truck and start having problems. I have looked into the hand held custom tuners. I don't know if I like that idea with aftermarket parts as they are not taking into consideration what you have done to the truck. Does anybody sell hand held tuners with multiple custom maps? What I would like to have is a hand held tuner that has a custom tune for my setup using 87 octane gas as well as another tune using 91+ octane gases. The reason is where I live there is only 2 gas stations in town that have 91+. Soon as you leave town no ware has anything other than 87 or diesel if you are lucky. What I don't want to happen is to find myself in one of the small towns where 87 is it and I need 91. I don't want an 87 octane tune if a 91 octane tune can get me more HP for the same cost. Anyway any help or suggestions would be much appreciated.