First, go ahead and get a set if you dont already. #1 best bang for the buck suspension modification out there. As for tires, I highly recommend a wider than stock tread. The Z is just way too heavy for 245mm R compunds to hold still. I was constantly finding myself pushing outwards during sweepers on my Yokohama A008RSIIs. Simply not enough grip but if you have a budget then the stock wheels w/ race tires is a good value. Not saying they dont work well, just saying that it could be better. R compounds can typically knock off 2-5 seconds off your lap times depending on the course.
John Yim (Houston) 91 ZTT Stage...stages are confusing. Just read the mods. :) SM2, Houston Region SCCA "...Just as they're about to catch me... Twin... Turbos... Kick... In..."