[xxxBlakexxx]

(crap, my post got posted before I was done)

Anyway, go with ones of these style chips:

1 - a "Max Tuner" type device. This will allow you to make changes yourself without pulling the chip. If you decide to add gears later, then just re-program it! No installtion with a tuner and chips suck to install, but these things cost more. Super Tuner and Diablo make these that I know of (though Diablo's may just be for Cobras)

2 - Choose a chip that can be pulled and customized later. I chose this option. For $80 I can add a custom program, but I have to take it out and mail it.

Now for your big question "On a Stock GT will timing advance and using better gas add to performance?" On paper "YES". In reality, I think it depends on the car. There are too many factors I think. This is why a real dyno tune program is the ONLY way to ensure results. Diablo claims a 24 hp gain at the wheels with my chip. I can tell you as the driver, no way. Maybe 5 or 10 based on my "butt-o-meter".

For automatics, garden variety chips help a lot more, yet cost the same. If I had an auto, a chip is a must! For a 5 speed, well, I am not sure. I probably would have been better off buying gears or exhaust.

Hope this helps and I am sure there will be other opinions.