Go into the EQ settings and try some of the settings that have been posted. Every person's taste of music and what they hear may differ so fiddle with it till you can get it just right..
Try ante up the 100hz a tad and then turn down the BASS setting and see if you can find a good balance. Sometimes it gets boomy and the under seat subs sound muddled.
Take a look in here as well:
http://www.m3post.com/forums/showthread.php?t=428114
Good luck