Here's a link to a past thread with multiple opinions concerning track tires:
Heat Cycling for DE Track Tires
I've been extremely pleased with the performance increase of combining Nitto NT-01 tires on 17" stock rims and M030 sway bars. I had the tires heat-cycled and they lasted a DE season on a largely stock '01 986 S. You need to increase the tire pressure in the front to equal that of the back, and you need to pay very close attention to tire pressures at the track. I tend to drive to the track and 36 psi, drop to 30, and try to keep them under 38 all day. Any higher and they get slippery, which invokes the ABS more, which heats up the brakes, etc etc.