'13 GT (brembo / track pack) Car came with PZero summer only, which worked tremendously as long as temp is above 50F. No plans to drive car in any snow however in NH we have quite a few days in the fall and spring that are obviously below 50. Wasn't ready to park it for the winter so ordered these with a set of ford track pack wheels.
Steering and handling - no noticeable change. Progressive break-away, recover nicely as well. Steering response / turn in just as immediate as the PZeros. Does provide a bit more feedback information through wheel (mostly because of stiffer sidewalls)
Braking - Under hard braking tire does induce more ABS action however still can generate similar braking #s. Wet road braking is probably better than PZeros
Ride / Comfort - Do ride stiffer than the PZeros. Road noise is lower. No change in tracking for car
Wet traction is great; equal to PZero. Zero issue with hydro-planning.
Dry traction is more than adequate but not nearly the bite that PZeros have (provided it was 50 degrees out). My best 0-60 time on Pzero was 4.2 with these it's 4.5 (according to onboard track app)
Overall = Good looking tire, tremendous in wet conditions, rides very quiet. Ride is stiffer and dry-road traction is 90% as good as summer only tires.
Tire-Rack Service : Ordered tires at 3:00pm on monday afternoon. Had them on my car by 10AM tuesday (next day). Wheel balance is spot-on.. no shakes or vibrations on speeds fast enough for a few week stint in the pokey ;)