I have had ultra high performance 225/60/16 tires on my GP in the following brands since new:
1. BGF XGT Z4's-Great tire and reasonably priced for a ZR rated tire-No longer available.
2. Michelin Pilot Sport A/S's-Very expensive and a decent all season Ultra High Performance tire. Personally not worth the money though, Cheaper alternatives in a Z rated tire that are just and good and will last just as long
3. Goodyear Ultra Grip Winter Tire-V rated-Used by most state police in winter driving-Excellent compromise between winter driving and very good dry handling.
4. BFG g force sport-225/55/16 Z rated-Ultra high performance-Summer only tire-Great tire for 3 seasons in the northeast-Reasonably priced-$93 from Tire rack.
Look for a V/Z rated tire if you are looking to dramatically improve the handling, steering, and traction over the mediocre OEM type S/T/H rated tires.