I still recommend that you save your a bit more money and jump to a Cayman S, which is a much better track car with the fixed roof. Some minor upgrades to the exhaust/headers and suspension will have you in very good shape. 300+ HP with lots of balance.
I was at a DE event last month and it was obvious the Caymans were performing very well at the track, even with novice drivers.
You can get a low mileage Cayman S around $50K, would think they will start dropping into the 40's soon.