Wayne,
Broke down and bought a pair of JBL 2242H 18" drivers. JBL intended these for sub-woofer duty for theaters. (For those who don't know how much they cost, they list for $839.00 each. You could buy a used car for that kind of money!!!Anyways, I am looking forward to using them in 9 cubic ft cabs with dual 6" ports tuned to 30hz. They are 99db/watt and are great for sub duty bandwidth limited to 80hz on the top end. Bottom end is 3 db down at 35hz.
I will have to get the specs and have you see what "Pi-alignment" would come up with!!!
Regards, Ron