I just discovered where the GT4 rear center brake light is located.
I always thought it was the light right above the Porsche GT4 emblems, but that must be the reverse light.
But it's way up on top of the hatch.
Learn something new everyday.

 

Yep, I think it's there on all current generation Caymans. Looks pretty good under braking.

 

I was not aware of that either.

 

The light above the Porsche is rear fog light and back up indicator

 

...yeah, just noticed the big red strip at the top of the rear window.