Someone posted this on another messageboard and I didn't know if anyone here has check these out. This place seems to make some huge JBL driven horns.
Realhorns
http://www.realhorns.de/bilder/fotos/photo_06.jpg
http://www.realhorns.de/bilder/fotos/photo_45.jpg
http://www.realhorns.de/bilder/fotos/photo_01.jpg
http://www.realhorns.de/bilder/fotos/photo_44.jpg