[GTR240]

well put it this way.  if you put one sub in one box then the sounds bouncing around will be of only one sub.  if two in the same box then that is double the interference in there.  you can add sound damping in there.  that will help alot.  i had a 12 in a box i made myself and it was a bitch.  well a bitch cuz i didnt have power tools.  but it was great afterwards.  my best answer could be this.  what music you listen to, how you listen to it, whats the space in your car, and other things you want.  so if you like boom boom then maybe a single sealed box will give you that...dont quote me...two single sealed box will give you a tighter bass.