What springs do u have on the back now? You probably need some shorter springs. My neon had struts all around but converted to coilovers. 2450 weight in its but i rane front and rear bars with 500 pound springs up front and 700 in the back. Was a little twitchy but rotated well.

I had an st focus on the street which is what your car is from what i remember. I would say that you need at least 500f 400r to start as far as rates with the biggest adjustable bar out bavk you can find. What shocks are you running?