Spot on Joe. And since free air subs are not designed to work in a specific controlled volume, the design of them limits the excursion of the woofer, which limits sound. So it would take lots more power to a free air sub to get colse to the sound of a sealed or ported box. Of course given too much power, the sub will again tear itself apart.

Oh and one more thing about my buddy's Bu, he spent some money, his tower seakers are 4 wetsounds pro 80's, but his sub amp there is something up with it. He can only play it loud for like 5 or 10 minutes and his amp overheats and shuts down. His solution? Turn off the stereo, wrap a bag of ice in a towel and lay it on the amp. His amp and subs must be wired where the ohm load is way to low for that amp and he is burning it up. Oh well, more money than brains club...