First of all, what is your current setup? I believe a Roush came with Bilsteins as original equipment. I ran a pair of Roush Bilsteins on my 95 Cobra a couple years ago and they worked great. If your car has the Bilsteins, a Tokico would be a step down. Find out for sure what your spring rates are now and what shocks and struts you have and then go from there.
From my experience with the SN95 Mustang, a set of Bilsteins with H&R Race springs along with a MM PHB will literally transform the driving manners and make the car much more predictable and fun to drive, without sacrificing a lot of ride comfort.
If you plan on doing an autocrossing I would recommend not changing anything in the car until you have competed a few times and improved your driving ability. A good autocross school, like Evolution, would help greatly in that area as well. Once you have done that you might have a better idea of what your car can do and if it has deficiencies that need to be addressed. Believe me, the greatest deficiency will be in the driver at first.