Man, 255 width Z2s are no joke. I was running on 245 width Starspecs the first two events, the new Z2s at the one we just had. Made a big difference.
http://www.empiresportscar.org/results/
To be fair though, the guy who usually kicks my ass in a meth injected SC'd Miata wasn't there.
Here's how the classes work by the way:
GTA-S = 8 cylinder N/A or 6 cylinder F/I, Street Tires
GTB-R = 6 cylinder N/A or 4 cylinder F/I, Race Tires
Etc.
Mods are unlimited.