switch phase when running inverted subs

I built a new enclosure for two 10's that is sealed with the drivers firing into the enclosure and the motors exposed. 

I found something on a non-audiuo site that said you need to reverse the phase of the sub (swap positive and negative leads) when running subs like this.  I thought about that, and it makes sense because when the cone is firing outwards and the sub receives a signal that would cause the cone to move outward, when the sub is inverted it would cause the cone to move inwards.

I've only listened to the enclosure for a few minutes at a relatively moderate level, and it sounded pretty good.  however, I had it wired up as standard; + to +, - to - so I'm wondering how much difference teh phase makes?

A) do you need to switch the phase?

B) how important is it to the sound?

Thanks,

Mike

The only thing that is crucial about reversing phase with inverted speakers is this:  in a setup where some subs are inverted and some are normal, the inverted subs have to have the polarity reversed to be in phase with the normal subs.

In a setup like yours where all subs are inverted, reversing polarity becomes a matter of what sounds best in your normal listening position.  The simplest way to wire them is the normal way as shown in the wiring diagram.  The polarity can be reversed by switching speaker wires at the amp, or using the amp's 180 switch.  Try both ways and pick the way that sounds best to you while also playing the speakers in the rest of the system.