So I just installed a new audio system and the rear speaker housings have a lot of rattles. What is the best way to stop it?

Also, the doors seem to rattle quite a bit too from my subs. How much of the door should I cover with dynamat and where is the best place to put it on the door?

 

Probably not something Dynamat is gonna fix. Doors rattle from a combination of worn weatherstripping, worn window stops, loose lock and door handle rods, worn out door latches, and dried out anti-rattle adhesive between the structural parts of the doors and the door skins.

If by the rear speakers you mean the 6x9s in the sail panels, it's usually because something isn't screwed down tight. People like to take the interior panels apart and never reassemble them correctly. Most of the panels have hooks and tabs that interlock and retainer clips to hold them tight to the body, along with screws that people often strip, or miss the hole completely, making for rattles. Also, the 6x9s are screwed to mounting plates which in turn screw to the body with a cloth/fiber baffle sandwhiched between. Often the screws will come loose, or get stripped, or the baffle breaks down, and the mounts start rattling. Also not unusual for the speaker mounting screws to be stripped.

Simply tightening things up can help alot. Replace any missing fasteners, pad any spots that rattle, etc.

 

The factory UQ7 sub boxes on my T/A rattled pretty badly, even with all the screws tight. A couple of the screws needed a single thread nut from the back side, but there were still rattles.

Adding some ribbon sealer to the gap between the edge of the boxes and body, and under the in-dash speakers really helped.

https://www.thirdgen.org/forums/memb...ml#post6021618

 

You'll need a barrier to absorb the rattle. Try Ensolite and Felt. Dynamat will help deaden the door (and help the rattle to some extent) but you need to find out where the "metal on metal" rattle is coming from and address the issue.