Buzzing from sub?, I'm getting an annoying buzz with my new custom sealed box Options

[Noahwhite2014]

So I made a sealed box that takes up the inside of the spare tire well and has a false floor baffle flush with the rear seats in the down position. The volume on the interior is around 2.85 cubic feet and there is cushion foam lining the floor pan in the back. The whole box is bolted down to the spare tire tie down hole and that is also the ground point I'm using for the amp. Here's a picture of it.

Looks great and sounds great, but at certain frequencies I get a buzz from my plastics in the back. I believe it's also buzzing the bumper and license plate bezel (not the license plate itself since it has a rubber "anti vibration" frame.

Anyone have a good way to quiet that crap down? Lol

[Bitter]

Adding mass to the metal panels may reduce or alter audible resonances but it won't fix rattles by itself. For the plastic panels you need to keep them from hitting the each other and the metal body, I like to use adhesive felt. I buy it by the roll and wrap the wire harneses in it, edges of panels where they meet the metal body and each other. For the bumper you need to either tighten the clips or install some stainless nuts and bolts that you can really tighten up to stop any rattling.