Most don't use chips any more. It's all done with hand held scanners than plug into your OBD2 port. The scanner will remove the factory "tune" then replace it with the "improved" tune from the aftermarket company (diablo sport, bullydog, superchips, etc.). They are also good if you plan on making other changes to the vehicle like changing tire sizes and tranny shift points. If going to the dealer for service you can can plug the scanner remove the aftermarket tune and reinstall the factory tune and they are none to the wiser. I know there are some out there that will take your factory ECU and reflash it if you are looking for a more of a custom tune. I know they do it a lot for GM series of LS engines. As for me, I have an 03 Chevy with the 5.3 V8 and I am still undecided. I am looking at the Bully Dog Triple Dog Gauge Tuner for it. It's vehicle engine tuner, monitor, gauge and diagnostic device all in a single unit.