The sizes you'll want to get for your '93 are 215/40-17 front and 265/35-18 rear. The RT-615K is one of several "extreme performance" tires available in these sizes, with the Dunlop Direzza Sport Z1 Star Spec and Yokohama ADVAN Neova AD08 available in addition to the RT-615K. All three are very good, but if I had to choose one, it would be the Star Spec. Although these tires offer excellent performance, their downside is somewhat rapid treadwear. If you wanted a tire that offers better treadwear, with slightly less but still excellent grip (way better than the tires you currently have), consider the Continental ExtremeContact DW. Note that the ExtremeContact DW is available in both the sizes you need from most dealers including Discount Tire Direct, although for some reason the 215/40-17 size isn't shown on the Tire Rack website.
I had the previous RT-615 (non-"K") and the only downside to them was their noise levels due to their large blocks of tread. The Dunlop Starspec was better in the noise arena with similar (if not better) performance.