Add insulation behind radio?
 

Hey all, I have been working on quieting down the extra little noises in my c5 z06 and noticed a lot of chatter coming from the transmission tunnel and behind the dash. I used some dynomat on the tunnel which helped a ton but I notice that behind the dash there is really no insulation and sound just resonates in there and easy comes through the ash tray area.

I was wondering if anyone has any recommendation for something safe to fill up the area that will absorb the noise but not risk electrical fire. Has anyone tried something like this yet and have any other ideas?