Welcome! I also have a 2004 GT2.
Wheel speed sensors (if that's what you're referring to) can't be changed by themselves. Gotta change the whole hub assembly, which might not be a bad anyways. Here's a thread for that http://www.grandprixforums.net/how-r...ubs-10985.html
Nah brah, GT2's aren't supercharged. 04 and 05 still had the GTP badge for the boosted cars.