sub magnet facing out of box.

You say they are "free air", but then you keep talking about facing them backwards in a box; which is it? Are they running in an Infinite baffle-type configuration or something?

-Matt

by inverting a sub...will not make them hit harder...

an like they are saying prior to this post... u must reverse the wiring on the inverted set...

The only possible advantage I see (besides asthetics) of having the sub magnet facing out would be to give you a little bit more volume inside the box. However, this will give you very little; AND, if you are hard up for space in a little vehicle anyway, having the sub with the magnet out will take up more space than if you had the magnet in and built the box to take up the space that the magnet was using outside of the box (if that makes sense).

If you were using 2 subs and turning one around made things sound better, the replies are correct, you had one of the subs wired backwards. 

I can't really imagine the situation where the airspace of the magnet assembly will impact the way a subwoofer system sounds to human ears.

But eitherway, inverting the subwoofer and swapping phase doesn't change anything about the woofer - save the aesthetics.

Depends on the woofer in question; some of them have motor assemblies that displace approaching 0.5 cu. ft or more., and I'm fairly sure you can detect a change in box size that large (depending on overal box size)...

-Matt