the guy that did 147 had it in a 35 cubic foot wall with 8kw if im not mistaken.

there are louder 2 sub non walled vehicles in bassrace

The jackhammer is a publicity stunt for MTX to get more popular. What they should have done is promote their 9500 series more because those are actually half decent subs that have some potential in them. But instead hardly anyone buys them because #1 there's a much better 9500 series sub out there and #2 its just the little brother of the jackhammer.