Re: oh yeah, it will be loud facing either direction! (nt)
I would have them facing towards the rear with the boxes up against the seat (#3). This will give you the most low bass, and strengthen your cabin gain somewhat. Only problems with doing this is: You may have too much low bass and not enough mid bass (this can be avoided with a proper enclosure), and you will increase the group delay (which can be a problem with ported subwoofers). My sudgestion is to build an enclosure you can position facing either way and try the latter of options and see what sounds best to you.
