I have Bridgestone Potenza Pole positions on my Boxster and really like them. They are quiet, fairly, good in water, and have a decent tread life. Mine is the RE050A model, which replaced the S-03 (which replaced S-02). They got great reviews on tirerack:
http://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Potenza+RE050A+Pole+Position