companies like american bass and SQ, whose woofers literally were carbon copies, they can hit lows well. one of my buddies i built boxes with for a while had a like 2000 buick regal. we did 2 AB's 12's, whatever their 1500w series was at the time. it was a subs up box, with an 8" sono tube firing back. HE HAD TO CUT OUT HIS REAR DECK BECAUSE IT BROKE SO BADLY. HE LITERALLY BROKE HIS REAR DECK from demoing so much and playing lows. i don't remmber what it was tuned to, but he was touching 25-26 hz with authority, and it wasn't all crappy sounding like the sub was struggling.