I've been real happy with my Yoko AVS Sports. They have been wearing fairly well (Several DE's and 7,000 miles and still plenty to go) (and Porsche typically eat tires) they are pretty sticky for a street tire - and they make plenty of noise before they let go - which is great for someone learning.

I've heard very good things from those that track on the RA-1 - I've also heard that the Kuhmo MX's are a big improvement to the 712's (which if you have them - better make sure you keep them blown up!)

I'll also Echo Loren on the recommendation that you stick with streets for awhile.