Just changed the pressure to 2.3. The car is much more spongy as before with 2.6. I also did a 0-100 and had 4.6 today - don't know why - 4.4/4.5 is what I normally get (same street as always). Might have been the lower pressure, or just a bad start. 

Also - keep in mind the Winter Pirelli is non run-flat, while the summer set up is factory deliverd in run-flat mode. They should be more stiff.

The test car I was driving was a 2012 car, it was insane stiff - was almost jumping on the road. Was equipped with summer tires but I also read that the 2012 was more stiff - way to much!