Ok to start off, my 02' EX has an amazing stereo. I got a double din Pioneer headunit that is ok. All my factory speakers have been upgraded to Rockford Fosgate. I installed 2 12 inch Alpine Type Rs in the trunk with a Hifonics Brutus 1200 Watt Super Class D. Its Loud. Im running my subs down to 1 ohm too. That's all fine and dandy but...my rear deck rattles soo bad its just annoying. If you watch it it goes up and down like a half inch at least and makes a lot of noise. Ive looked in the trunk and theres not a lot of places to put bracing or anything. Since there is metal lining the underneath I dont think hushmat or peel n stick will help me. Any ideas or past experiences, please share. I love talking to fellow Accord owners.

 

rattles can be silenced with weatherstripping foam. one main source is third brake-light against the glass. pretty easy to remove it, foam it, and return it.

rear speakers can also rattle - so weatherstripping foam to seal them can also help. removing rear speakers can also let more air through and reduce the pressure on both the speakers and the rear deck. if using rear deck speakers, it's recommended to seal them to prevent pressurization from the subs.

i have about 5 layers of deadener on both top and bottom of the metal rear deck. the rear deck is just cardboard and carpet - so it's not a concern.

 

deadner, deadner, deadner. it does help. anything you can do to help reduce flex will lesson rattles as well. you could pull the panel and carpet it as KHA said. foam the center brake light.

main thing is to isolate the rattle, which can be tricky. once you have it isolated you can begin to fix it. the whole deck is a big problem. but do it piece by piece and it helps quieten things down.

also the less everything else moves, the louder your stereo gets.

 

Ok cool. How do I remove the deck and the light assembly. If I can do that it will help a lot .

 

it's pretty easy.

from memory, here is everything you need to remove:

third brake light is held from below. it clips into place and the bulb rotates into place.
the rear speaker grills are held from below with two screws each.
the child safety latches are bolted down, remove the plastic covers and remove bolt (14mm or 12mm)
the middle seat belt assembly cover is held with a phillips screw, IIRC.
the C-pillar side panels are just held with clips.
the rear seat is held with one 10mm bolt in the back then just clips in front.
the rear seat side bolsters are held with a 10mm bolt on the bottom. they just lift up.the plastic trim around the top trunk opening plastic trim just fits in place.
now the rear deck just lifts off - pull towards front. thread the seat belts through the slits.

it's not trivial removing the rear deck... but not hard. i can do it in about 20 minutes... but i've stripped the car down several times.