Port and Sub aiming

I will be doing an install in a '93 BMW 325i soon, and I need advice from you guys about aiming the subwoofer and port. What I want to do is install the subwoofer behind the flip-down center arm rest in rear seat. I have a 16"x9" hole there where i would like the sub to be visible. Importantly, I would like to get the most SQ out of the subwoofer. It is a 12" RE Audio SX in a ported 2.0sqft box(RE specs). Where should i put the port? In the armrest hole or in the trunk? *note the trunk is very well sealed off besides the armrest hole*

Or do you guys have a different idea of mounting the sub? Im going for a more stealthy and clean setup.

Thanks a ton,

Luke

I suggest that you will soon get over the fact that you have a subwoofer in the trunk and so will not need to reassure yourself of its presence by glancing in the rearview mirror at it!

You will likely find, if you take the time to test it, that aiming the sub toward the rear of the trunk will get the best overall sound.  The port should point in the same direction, and most car audio vented boxes are designed with front-firing ports.  Leave the armrest open while listening to allow the full subwoofer sound / air pressure to easily enter the cabin.