in that case, I would do 1 Digital Designs 9515 and anywhere from 2k-3k watts rms. If you can get DD subs at cost I would love to see your price.

really the possibilities are endless, so you will have to decide what you want to do. Any decent sub will rattle any interior. I say DD because they are some of the loudest and most reliable subs you will find. These things can take a beating and not slow down.