[69gmcc10]

For economy nothing will be better than a good tune. If it were me I would swap out the muffler and only the muffler (stock pipe diameter is perfectly acceptable) to a less restrictive unit like a magnaflow and then order a tune form Black Bear Performance. There are several kinds of tunes but the easiest and most affordable options are sending in your computer a have them flash it with a preset tune with optimized parameters or order there cable to link your truck to a computer and give them some specific data to build you a custom tune for your truck they flash your computer with when you send it in. Both options are good. The only other thing you can do is regular maintenance to your truck so it is running as optimally as possible.