I put some sound-deadening stuff (like Dynamat) on the back of my third breaklight, and sprayed some expanding foam in through the hole while it was out. If you use foam, get the MINIMAL expansion stuff. The max expansion could warp or crack the wing. Also, put something under where you are sparying, you do not want that shit on your paint! If you want to do it right, pull the whole wing off an also spay the foam up through the supports. I didn't, but the buzz is pretty much gone now. It's caused by the wire for the third breaklight vibrating inside the wing, there isn't anything holding it in place, and that's what the foam does. By the way, I'm running a single 10" JL Audio in a sealed box, 150W going to it, and I still had the buzz. Expanding foam=cheaper than new sub box.