I like the 225/45-13's alot. (Gen 1 Rx-7 in ITA). They fit under the fenders more easily than the same size Hoosier, and are a lot more forgiving if tire pressure is 1 psi off. They do feel like they go off after ~9 or 10 heat cycles (lose ~1/2 sec / lap). I treat them just like Hoosiers, and so far so good! Not as easy to flat spot as a hoosier, but probably just a tick slower when both are set up with perfect pressures (but then I rarely get the Hoosiers just right--so the pressure forgivness on the Hankooks works great). Oh, and they are cheaper! I've been running the C50's, but am tempted to try the softer compound.
Tak
#29ITA Rx-7
SFR SCCA