So I put the K&W spring kit it does allow some adjustments to the ride height, but you have to compress the springs to change height. Koni sports are adjustable and let you change stiffness easily. STRONGFLEX sell polyurethane bushings for the R170 MB that you can use, also you might want to look at the Brake upgrade you can do with the 345mm front disk, I did a big right up on it with photos in the brake section.
MJPowers use to race a XFire and can give you some info if he still monitors this site, I bought some of his racing parts when he moved up to a fast class.
Dan