Well, most people face the subs towards the rear for a several reasons. The most popular reason is since Low Freq. Bass (Which is what is coming out of the subwoofer) Has very long wave lengths, if your looking for low notes its best to have the sub as far away from the cab, within reason. At least that is what I have heard. I understand that there is sorta a sweet spot in every car.
It does depend on what type of bass your looking for and what type of music you listen too.
Me personally, I was going for SQ so I faced my subs forward. This tightens the bass up, but at the same time restricts the bass.
I have yet to try my subs towards the rear, I might do that in the near future just to see what it sounds like. My only complaint with the sub facing the front is they tend to vibrate the seats and the rear deck. I just bought some dynamat to solve this problem, hopefully!

I don't claim to be an expert on Car Audio, but I figured I might be able to help. PPL Please correct me if I am telling lies.

Later,
Justin
Originally posted by RobDog117:
can someone explain to me why you would point your sub box facing out the back instead of towards the passenger compartment?