The gains you see can range from 7-10% at the rear tire on 9's or 12's. As far as putting one on, they are still very street-able and actually makes them more fun. I drive my XB9R to work every day and I have had a race kit on it since the second day I owned it. I love it. The thing is now though, you can't really find them anymore. I have to hunt all over the U.S. to find them at another dealer so I can sell them over the counter. I know some aftermarket sites have the set ups too, so I would try there also. Let me know if you want me to find you one.... :D lol