I bought the Star Specs as a replacement for the anemic and horrible Goodyear RSAs that came on the G8. My upgraded GT model was putting down well over 400hp and would roast any tires unless you were already highway speeds. I put the Star Specs on and was absolutely blown away at the night and day difference in steering response and traction. My 4000lb car felt 500lbs lighter and more nimble. I autocrossed the G8 at local SCCA events about 10 times and was pleasantly surprised that the car became competitive. The turn in is very quick, the stability at highways speeds is incredible, and the dry traction in insane. Your level of control is nearly endless as it is very easy to tell when they are reaching their limits. I didnt win any trophys but it was 100x more fun to drive.
I drive the car every day on NYC streets and when the weather is colder they can become a bit jarring on rough roads but in the warmer months they are amazing. My recommendation to prolong tread life if you are autocrossing/tracking them is to buy a $15 water sprayer (like the ones used for pesticides) at your local Home Depot and make sure to ligthly spray them down every couple runs. It'll prevent them from feeling oily as they reach higher temperatures.
I just bought a set for my girlfriends 2010 GTI and I will be buying another set for my 2013 BRZ Limited when it arrives next month.