Most likely, a plexi glass would seal better(most likely it will cost much more as well). Once in a while, the tire pressure decreases, then I tighten the ratchet. Eventually, I will have to take it apart, to fill it up.
I don't want to mess up my floor board. I carry TVs and other stuff and I don't want the grill to scratch something. I have the original JL grill, but it is to tall.
The sound, comes through the floor board, no problems there. I'm using my sub level, at -11(!!) on my Kenwood DNN991HD.