i had the same problem with my subs i got installed a while ago in my bimmer, they didnt sound like they should have and it turned out the wiring they used from the battery to the amp and amp to the subs was wrong. they used speaker wire instead of heavy duty sub wiring, i guess thats what you get for having it installed at Circuit City

 

thanks for the help guys, i pulled out the sub that wasnt working, and the negative wire had came unattached from the sub. i was only hearing one 10. with them both hooked up, it pounds!!! hell yes!