Hi Al, didn't have the Fostecki long enough to make any meaningful comparo. Put those together for a friend and shipped 'em.
Jordans need a sub if played with anything with much bass. But I don't think they do loud well in any case. But they are IMHO very enjoyable for chambers, vocals etc, mostly I don't bother with the subs.
Good guess BTW, I think they are 35 liters.