Porsche have done a very good job over the years or overcoming what is an inherently poor design for outright track performance, with their incessant tweaking of the 911 formula (seems sows ears can be turned into silk purses), whereas Nissan just built the car with the best dynamics they knew how to from the outset, and the proof, as they say, is in the eating; Despite being inferior in every way to the Turbo on paper, the R35 continually murders 911's on track.
It's telling that Porsche keep the Cayman hobbled to protect big brother's sales, when it's a much better design for outright performance than the 911. While ever Porsche is chained to that marketing reality, Nissan will keep kicking it's head.