Just thought I'd add my tuppence-worth regarding tyres, after a bit of research on the 'net, I've just had a set of Continental's latest SportContact 5p's fitted to the GS. They weren't cheap (£850.00 from my local specialist - Skidz, Falkirk) but instantly the car seemed to ride better and feels smoother than on the P-Zero's previously fitted. Corner turn-in also feels like it has more "bite" than before. Plus as a little added bonus I reckon the tyres look fatter on the rims somehow!! they seem to have a "plumper" sidewall profile/shape than the P-Zero's!!
Mark.