No idea about GS as only been a passenger,but I can vouch for the P-Zero Corsa an a 3200.
Awesome.
My car was a buking bronco on any other tyres, spinning up the rears, aquaplaning and generally trying to kill me. In an exciting and fun way.
Fitted corsa tyres, beofre european road trip. Tackled the infamous stelvio pass (and many others), with melt water streaming down the road form 4 feet high snow at the roadside. All grip, no slip and I mean hard acelleration, not even spinning up an inside wheel. 3000 miles later we are back at home and still driving confidently in wet, cold UK conditions.
My car is transformed and will live on these tyres in future. I too had my doubts after hearing all the stories, but this is my real world reportage. Any other drivers had them fitted?