New Direzzas at the front seem to last forever; they still have very deep treads at the front; like new; literally. However at the rear, tires were scrubbing and lasted to an expected 8000km, due to major toe-in suspension condition at the rear; not the fault of the tire.
Z1SS felt less traction than XS due to the fact with XS, the suspension had -2.5 camber, much more aggressive. The tires are a major contributor to making handling better, suspension tuning brings out the tires full potential in handling. I suspect the Z1SS may handle better with an agressive setup (same setup as previosly mounted for Kumho XS) Handling felt more like sub R-comp with slightly lower psi and was a little more forgiving yet still sharp. At higher psi, and purpose tuned suspension the handling is quite sharp, very sharp. Rear tires have 10% tread left, zero tire squirm (due to previous excessive toe-in; front tires have 95% left. Highly recommended to tune suspension & driver to match.
They will give you excellent try traction, yielding different driving lines at the track and they stick so well at optimal temperatures that it really is difficult to find the limit of traction; These tires will give sub r-compound like traction for competative, HDPE and standard road application use. I would highly recommend any driver try Z1SS before using R-comp. These tires are the BEST choice for a road use, HPDE, light competition, and daily commute; at a reasonable price too. This product has an excellent position on the market.