I ending up going with the PROJECT 6GR TEN GLOSS BLACK FINISH R-SPEC GT350/GT350R. It came down to these and the P51's. I chose the 6GR TEN because they have more brake clearance, second lightest rims, and they're local.
I'm not sure which tires yet. Leaning towards the MSC2's but with petstang only getting 2 or 3 track days, I might give the Goodyear's a shot. They're about $300 less per set.
Petstang, you mentioned you'd probably go 305/315 next time. Is it solely because there's not enough gain to warrant the extra money?
No, my only reason to go to a square set up is to eliminate understeer - based on feedback from this and other forums