2001 mustang gt
I personally would not use a chip. Buy a handheld tuner for a few hundred bucks, and get free tunes for life. I had a diablo chip, and it malfunctioned and wrecked all sorts of havoc on my car. Bucking, made it run lean, and was overall a bad experience. Granted the chip was put on at least 8 years ago, and things are bound to happen. But with handhelds out now, it's just a better choice.