I'm running an American Bass TNT 15" in a 6cb.ft. box tuned to 28hz. I have both port and sub facing the hatch (I drive a Nissan Pathfinder 2001 SE 3.5) and, needless to say, the entire hatch flexes like crazy... especially towards the bottom with the licence plate. The rattling is especially loud at 40-50hz but not so much below that. Anyway, what type of sound deadening foam would you guys recommend I use on the hatch? And for some dumb *** reason my licence plate doesn't have bottom screws so I guess I could just shove some foam under it to stop the rattling there.