does your box take up your whole trunk?
if i had a trunk i think would go IB,
subs are just like your mids, & tweeters, placement does matter,
if you have your subs facing the trunk it will give you a litltle more lower frenquency into the cabin, but if you like the way it is keep it that way.
SQ takes time to learn,
I will be looking forward to seeing your pic