Fully adjustable coilovers (Teins aren't bad, JICs are better)

Sway bars (RMDSM, preferably)

Poly bushings (Prothane, preferably - stiffer and easier to install)

Upper shock tower bars (all of them are crap, except maybe for the Neuspeed. RRE makes a nice rear)

Lower tie bars (RRE makes a nice front, I am looking at it, in my hands, right now)

Good, lightweight, wide wheels with sticky rubber on them. Go as wide as can you fit. Roll your fenders for more width in back.

Racing seat and harness so you can actually steer the car the way in which it is capable of being steered.

Breakes should be upgraded, as well, as it does not make sense to have a car that handles phenominally, yet requires early braking on corner entry.

If you are truly crazy, get a roll cage. The more chassis mounting points, the better. This will reduce flex more than anything else that you can do to the car.

A smaller steering wheel would make it easier to steer the car, as well.

Weld a steering quickener in. Fewer turns lock-to-lock can be fun!

As for shock tower bars, the adjustable ones are crap. The rear ones with a couple of 90 degree bends on the stantions are crap. RRE has a nice rear bar that will fit your car, but the front says that it will only fit the turbo models. I think that it would hit our valve cover. The top of the shock is not the best place to reinforce, though, as the forces are transmitted to the A-arms instead of the shocks. On a car with struts, it makes sense to bridge the tops of the struts, but with shocks, reinforce the A-arm mounting points.

I don't know of a good rear lower tie bar. I am also not entirely sure how necessary it is, given the strength of the rear crossmember. If you think it would help, get some bar stock, some plating, a brake, and go to town. I would recommend the same for the front shock tower brace, too. Try connecting all four upper a-arm mounting bolts together, and triangulate it to the firewall.

Lastly, check the obvious shit - wheel bearings, bushings, bolts, arms, and ball joints. The best suspension in the world will not eliminate a wheel bearing problem, or a dying ball joint.