Check for worn Wishbones, track rod ends, ARB drop links, top mounts, cracked springs and knackered dampers. There are uprated dampers and springs, but mostly people replace the rest with OEM parts.
sparco top brace, and scout round the parts for sale section for one on nigel's recent group buy ones - probably looking at over £200 for both, but do add a stiffer, solid feel to the car
Get it all done with replacement OE parts and uprated springs, dampers, AR bars and upper and lower braces and it will feellike a different car altogether. Promise. And I haven't even fitted my camber bolts yet!