Just received mine today. Do you change the tire sizes and speed limiter after installing a performance tune by modifiying the parameters of the installed tune? And do you program in stock tire size first and then the current tire size? Thanks in advance!

modify the parameter first to save you time.

Thanks. I just messed around with it and it was pretty straight forward. I never could get the On-Star light to go out. But everything worked out. Now to drive it all over until it shifts right. http://www.dieselplace.com/forum/images/smilies/biggrin.gif