02StangGT is right, the governor speed limiter is programmed into the PCM, and you do need a tuner to get in there. PCM tuners run around $400-$500 plus another ~$100 for a credit to actually change the PCM, although it can be read for free without using any credits. You have a few options when it comes to this, buy your own tuner and DYI, go to a shop to have them do it, or you can often find people with tuners that will help you tune it for the price of the credit(s) you use and maybe a few extra bucks. My dad usually has people on the Corvette forum that ask him to help them do that since he has an HP Tuner.