What are you trying to improve?
There was a thread about this that said strut braces were a bit of a waste of time on a street car*, and that if it was a track car a cage could add far more strength than a strut bar anyway. - Whiteline recommend you start with polybushes; stiffer ones where you want less movement. So for example if you're trying to dial-out understeer, polybush the rear before the front so that it rolls less an therefore looses traction before the front does.
I think they then suggest the rear ARB (obviously they suggest their own product), then polybushing the front.
Is it just springs on standard shocks? If you'd got coilovers you could look at doing things like the castor mod, but standard struts (and top mounts) rule that out.
Have you played with the tyre pressures? Don't forget there's far more weight at the front than the back, so it needs higher pressure (I think most people run +2PSI at the front compared to the rear).
*I'm not saying that they don't help, just that you don't need the most stiff car on a road because you sacrifice comfort. It seems to me that a 20-year old chassis could probably do with as much help as it can get.