which way should my subs face?
 

should my sub be facing outside the trunk or towards the inside?

I find firing the subs towards the back of the car ususally works best the only way is to put the box both ways in your car and listen.

should be best facing the trunk. try different position like ^ said. Mine were equal both ways.

since you have a hatch, facing up might work best

try up and try rear

if you have a ported box, port facing rear and sub facing up would work best most likely

In a hatch if the enclosure is sealed then facing the sub straight up will yield the most cabin gain.