Thanks Bruce. I'll see what REW comes up with as far as filters to apply to the above response curve. The subs are permanently mounted in the corner of the room firing at a 45 degree angle across the room. You can just make them out in the front left corner in this shot. You can also see from where I took my measurement.
And a close up showing the 18" drivers (each in their own 336 liters net enclosure):
