tuner for 5.3

[LEEVON]

I would recommend a custom tune like 1969x11 said. You will get more bang for your buck. I gained about 3mpg on my tune from wait4me and a whole lot of performance. It was a duel octane tune, which really kicked in when fed 91 octane. I don't think it will hurt your engine, but some tuners will not do real high mileage. If you read on some other boards, the consensus has shifted from wait4me to blackbear for less expensive tunes. In my opinion either will be a major improvement. You can also get a tune strictly for mileage, but I don't know how they perform.