Here's a sub project... if you got the room!

[karl k]

http://www.passdiy.com/images/projects/el-pipe-o-f11.jpg

and it's got an interesting story as well as plans!

http://www.passdiy.com/projects/el-pipe-o-1.htm

[Arc45]

I gotta say dude that that is the wildest sub set up I've ever seen! Are you looking to create 5.0 richter readings?