Here it is. Graphs and iterations galore. A cool thread for sealed info.

http://www.hometheatershack.com/forums/svsound/77026-dual-sb-2000s-flat-10hz.html

I have no reason to suspect Axiom sealed units would perform at anything less than these tests suggest. Two ep500s sealed would probably be similar to the test here. Maybe even 2 ep400s.