olddog

Chips, actually snap in PROMS or a custom tune, make a huge difference. The key is to have your car tuned to your car's responses to the changes; that is, some will need more or less fuel/timing etc. Each unit is different to a degree and some are mush more particular in what they want then others. This is why you get a custom tune or custom PROM and not one that is off the shelf. I have had four cars custom tuned by Jeremy at Fasterproms: three Vettes and he does my STS-V on Monday. My experiences have been very noticeable increases in performance and some in mileage. He even improved the custom tune on a Lingenfelter stroker Vette that I had. I think the 'bought' tunes off the net are fair at best. If you get your car tuned know what you want and make sure you do not allow just anyone to tune it; an incorrect tune can cost you much grief and $$