Tuning yourself falls into a few catagories. Basic tuning is really easy, such as changing rev limits, fan temp turn-ons, and those simple constants. Good for a bolt-on car, which is why mail order tuning works so well for bolt-on and stock cars. Advanced tuning involves a lot more, such as changing the timing for cams, heads, and strokers, as well as adjusting the auto transmission (this kinda goes into a catagory itself, because there is SO many variables on the 4L60E). I probably spent a good year learning about tuning before I started working on my car, and then another 6 months before I started doing tuning for other people. You can destroy an engine or transmission if you really do something wrong, so it's not something you can just pick up and start doing overnight.