I just installed a new 8" sub in my FD, and was wondering if I should face it to the cabin or towards the rear? Which way will sound better?

Also should I phase it 0 or 180 degrees.

Thanks

 

It won't really make much of a difference which way you aim it. Very low frequencies are omni-directional. The benefits of aiming the sub away from you are that you don't hear cross-over leakage and distortion as easily.

Phase (or more likely, polarity in your case) is completely system dependent. The best way to set it is to play a tone at the cross-over frequency through your entire system. One polarity setting will be louder than the other one. That is the correct setting.

 

I have mine pointing at the glass in the hatch and it sounds good to me.