Sentras with stereos

Ok, so I have 2 alpine type r's 12'' in a ported box in the trunk of my 2001 gxe, when i play bass the entire rattles like crazy, im sure other people have encountered this problem and im wondering if anyone has found a way to counter it, One thing i was thinking was facing the subs to the interior of the car instead of the trunk, and I was also wondering if anyone has attempted to dynamat their trunk and did this make any improvments?

second skin. its better than dynomat.
http://www.secondskinaudio.com/cgi-bin/index.cgi
pound your car with the subs, checking for panels that are loose. push those in.
your license plate should be held in place with rubber washers in the screws. im pretty sure most of your rattling is coming from the rear 6.5 speaker shelf kinda thing.
front doors, make sure there is nothing in them that is plastic, otherwise that will rattle.

Do you have a spoiler? My spoiler rattles a little bit and there really isn't anything you can do about it.

yes there is. dynomat or phatmat works wonders. as for the wing try tightening down the bolts that holds it into place. If you are looking for better sound dynomat under your rear speakers, your door speakers roof, and the whole trunk including your lid. that will also help you gain a db or 2