Here is some advice from a "Mustang GUY" for your modifications. If you're stock and the Mustang GT is stock you'd better be a good driver if you think you're gonna beat one in a flat out 0-60 or 1/4 mile race - the reason is torque....make sense? I'm not being a dick I'm trying to help you here. My reccomendations are for modifications to boost your torque (I'm not sure what they are for your RSX). The type S has good numbers for horsepower but you're weak on torque compared to the stock Stang. It WILL hurt you if you road race and race up hill. Simply changing your tires will NOT allow you to wipe the floor with a Stang - that is the honest truth. Once you are ready to race be careful what you try to bite off......if the Mustang has many bolt on modifications or a supercharger good luck catching it. There are 4.6 liters out there putting out between 700-1000hp and they "look" normal. Also a popular motor Stangs are running is a 427 stroker - try to race one of those you're in for a serious ass kicking - you can't make the RSX touch it no matter what you do to it. They don't call it the 427 "Smoker" for nothing. Other than those cars to watch out for, with a few modifications you will be running close with the stock GT's and beating them.....but don't expect to wipe the floor with anyone. I know you guys will all hate me for saying this but I test drove a Type S and Mustang and I bought a Mustang because it had more power and more potential for midifications.