Peel n Seal from lowes, its cheap and will prevent rattling

Add mass to the panel. Easiest way is dynamat as shown above. Or wedge some shims around the perimeter and between it and the metal deck area (where the speakers typically mount)

I see, so I just need to apply it under and on top of the deck?
I'm really stupid at this, but how exactly would a sound deafener stop the rattling? I know that if u apply it to your car it keeps the noise from going out and keeps them inside the car, but as far as stopping the deck from rattling idk how that works out

I was really thinking I need some kind of a soft material like foam or something place on the corners of the deck and that would stop it from hitting the chassis of the car.

sorry for my stupidity btw, I'm quite new to this hehe

You put it between the panel and anything it's banging against. So wherever it's touching metal and vibrating against, toss a layer of the sealant on it. Or just PL400 that bitch down.

Damn yeah so I took a better look at my trunk and deck and I noticed that the deck is actually part of the car. I do not think it's removable
it's metal and it has fabricate over it from what I saw.
And I'm 100% sure it's the deck that's rattling. I put on a song with high freq. bass and I tried to put some weight on the deck with my hands and it actually dimmed down the rattle.
Now I just gotta see wth to do with it...

if its metal the easiest thing would be to weld something sturdy under it to keep it from flexing.

Wouldn't that be kinda dangerous tho? going inside your trunk and welding, right above your gas tank?

nah its fine. chances are it'll just take a few 2 second welds and be good to go.

Mmk
thanks for the help bro, as always