You are absolutely correct TRK!
When it comes to actual aero performance, I can say that at 150Mph it becomes REALLY light in the front, not very planted I´d say. Besides the top vents I´m also adding a decent splitter, I think it will be just about right. Pics will come when I´m done! :-)
Regarding the other thread I´m referring to, I hope I´m allowed to share links to other forums, if not please let me know. Here is that thread anyway, there is a guy (jimk04) who has made a really neat installation, however I believe that it´s a bit too tight behind the rad, so I doubt its optimum from a aero perspective.
http://www.planet-9.com/987-cayman-and-boxster-competition/208657-center-radiator-venting-holes-question.html#post2011233
TRK, you are correct, the GT2 duct can be fitted as intended if the side ducts are trimmed, to rough for my taste, wanna keep the side ducts neat and tidy.
Anybody with opinions on the tilted rad? Air bubbles or not?