So a package came for me today. I installed the 18" in one of the band pass cabinets and hooked things up temporarily for a test run. The 18 is tuned flat from 20-40hz, then the 15 is tuned ~40-100hz. At 1400w the 18" cabinet jumps off the floor. I have to say "big bottom" has been achieved! Now I gotta build cabs for the house and retire the phase linear and other vintage equipment to the living room! Tomorrow I'll finish the wood working on the cabinet, start hanging them from the ceiling and installing the gear in it's permanent cabinet.