he only has 400 to spend. and what are MTX 9100's?My thoughts exactly. For 600 you could get some alright woofers but no amp. I would personally get 2 mtx 9100's for insane bass or just one. That right there would be 600 not even including an amp. A buddy of mine has one and it is almost to much to handle, with a good box and a nice amp you could get it for about 800-900 for a perfect set up
With what?no.. at least i wouldnt suggest it. you can get louder and somethin that sounds kinda close to as good for a lot cheaper.