First off, i have a thunder 4000 12 in my Z and it pounds!! Its being powered by a PPI competition amp. And what bout the low end MTX stuff....All the thunder series is the high MTX stuff!! The 4000, the 6000 and the 8000 are the best subs MTX has out right now! So in a way you could say that the 4000 is the lowest of the best series that MTX makes... I got my 12 for 90 bucks on sale and it hits really hard!! I'm very happy with my MTX!! I think it is a respectable audio company!!