Did a little calculating......CG about 65% "up" when inverted....airflow about 75ft/sec.....on an average day in Canada with cold, dense, high humidity air, the corrected thrust level from the port acting upon a 103lb speaker in the inverted orientation if operating 180 degrees out of phase with the woofer cone giving an accumulating force on the cabinet(without grille)and if the cabinet is oriented(aimed) >7degrees "up" creating a slightly unstable.......