Not much to go by...
If your suspension is still stock, a set of KYB struts will transform it greatly. While you're at it, install a set of Plaia Pivots (bearings) in place of the phenolic washer.
A front anti-sway bar on a street driven X keeps it from leaning nicely without getting into super stiff springs. Don't add a rear one.
185-60/13 tires are another option if you're currently on something taller and skinnier.
Now, if you're talking track/autocross it's a whole other ball game. Lots of help to be found in this regard here as well.