Ugh, here I go again.

Since school has started back, it's put me back into the mood to start modifying my stereo. I am NOW thinking about a slim-line subwoofer from either Pioneer or JL. I'm all of 5'8" so the room behind the seat wouldn't be an issue. I know that cars such as the 350z have a sub behind the driver seat, but is this irritating?

Also, I am not sure if I just need one or I should opt for 2 subwoofers for the bump that I want. Has anyone tried the slim woofers in our cars yet?