No offense to the OP but since he's asking about this I don't think we should be recommending him the Sniper system since I don't think he's got the knowledge to tune his own vehicle nor a GT500.There is a tuning system called Sniper that you can tune two separate cars with. I haven't personally used it but have read about it. It may run from a laptop instead of a handheld unit. Google it, I think it'll be easy to find. I think you can buy what they call Bullitts, that allow you to tune maybe a few more than two cars from the same system.