Please read The Ancient Audiophile's Quest for the Ultimate Home System for some more thoughts on this subject. I have found this reference to JBL Professional , but they don't seem to list individual drivers on-line. I guess you have to badger an individual distributer for this information. Even though I haven't got the rest of my system to those standards yet, I did do some additional research on drivers that would be suitable. I am really intrigued by the McCauley pro sound drivers.
All information is downloadable.
These are VERY heavy duty woofers, designed for arena-type PA sound systems. Capable of delivering 132 db at 20 Hz. I believe the target audience for those drivers is discos and dance clubs. You also might want to check out the Horn Speaker Home Page. Personally, I don't believe in horns and try to avoid them, but your milage may vary.