Question about HPP3 programing.
My programmer has been just sittitng in my closest for a few months now. The reason I have not used it is because I do not know if my car is running a stock tuned, the guy who owned the car before me might have had it tuned. My question is will the Hypertech just replace what ever programming that is already in the computer with it's own? Or can the programmer only work on a car that has not had a modified ECU?
Thanks
Thanks