I'm really glad to hear that you're keeping your Z, in my mind there's nothing on the market to beat it for price and looks. I 'm also in the process of looking for 20mm spacers for the front. I've already got 25mm spacers for the rear and in my mind you can't go wrong with Eibach. They may be slightly more expensive than other brands but they have the German equivalent of road safety certification. For tyres, I have just bought a pair of Hankook V12' in 245/45 x 18's and find them really good in the wet and also in the dry. If they do have a problem and its only a problem if you do regular track days and that is the sidewalls are softer than some other cars, but for everyday driving they're not an issue. I drove on T1R-Proxes before and to be honest I couldn't tell much difference on the road.