im have to 10in jl w3 qnd something is shaken towards the back. i have the Si. anyboudy that has had problems shaken in the back on th 4gen lude

 

do you have a spoiler ?? maybe license plate ?? empty cans ?? midgets ??

 

get some dynomatt, turn the system up and listen to where the noise/vibrations are coming from. and then dynomatt around where you hear the noise. common places are like he said, license plates, wings/spoilers, and basically all of the trunk lid.

 

i have dynomatt the whole trunk

 

common problems:

trunk lid...while bumping, put your weight on the lid, see if that gets rid of it.
lic plate...while bumping, put your finger on the plate or plate holder.
rear deck...while bumping, put some weight on the rear deck.

is your spare tire down good? are the tools in a place where it doesnt move around? maybe its something in the gas tank?

 

if it is coming from the trunk lid, something that will sometimes help and costs no money ( i did it in my lude) is to open the trunk, and loosen the two hexbolts holding the trunk latch, push the latch ALL the way down, then retighten, seems to be more secure afterwards.. less shaking for me