how hard was he running them?
i was doing a little testing with mine the other day. i beat on them pretty hard, first with an orion 250hcca(bout 800 watts to the pair, 1ohm) then with an old school hifonics amp(bout 750 per sub, 1ohm) . they seemed just fine. a little underdamped, but i suspect that was because of the 1 ft/sq box, and the 1ohm load. the roof of my truck was flexing about half an inch in places. much harder than i run stuff under normal circumstances, but like i said, i was testing for an install in my other car