I'd be very a'scared of launching that 1500 lb subwoofer compression chamber cover like the Hubble Telescope on a good Timpani roll. Yikes.
Check this out...you might implode.
Searching through the net, found this site. If high efficiency speakers are your bag, check what these guys are doing. MOST LIKELY, it is going to sound terrible, but all of those guys out there with their "boom cars" complete with four JL 18" subs will probably wet their pants. For those of us who actually care what music sounds like, this'll be a good laugh. www.royaldevice.com/custom3.htm