I don't think that I'm fallowing, atomic pinkie. do you mean opening a window as the 'port', or did you actually 'port' your rear deck(under the rear window)??
I couldn't agree with you more as to the sound reproduction of sealed boxes. I've got 4 10's in a sealed box, and it pounds.
And as for shaking stuff apart, hmmmmmm, let's see, there was the rearview mirror, the vent shades, the door speakers, and countless little nic-nacs from the interior.
Please do post back with more on how your car is the port. Thanks.