why would you have to reverse the polarity?

 

Yes, just reverse the polarity on the amp. You need to reverse the polarity because of cancelation. Some vehicles do sound better with the polarity reversed even with the sub in the normal facing positionbecause of cancellation, but most need to be firing the same as the rest of the driver's in the vehicle. So when you mount the sub backwards in the enclosure, you need to reverse the polarity to keep the cone moving the same direction.

 

You don't have to reverse the polarity because they are inverted. Changing the phase is irregardless to how the subs are mounted to the enclosure. Yes, it is true that changing the phase on inverted subs may sound better. It is also true that it may not.

Hook the subs up the way they sound the best.

 

I totally agree with running them how they sound best, but if you have a sub that's foreward facing with 0* phase, and you invert that sub, chances are you're going to have to reverse the phase to 180* to get the best results again. The cone should be moving the same direction. Changing the phase of the sub not only changes the sound of the sub itself, but also of the interior speakers because you are now running into cancelation with the midrange drivers. 90% of the time the sub should be at 0* phase (Cone moving outward first) to get the best results. Unless you have 2 subs that share the same airspace, then 1 should be 180* out of phase, ect, ect.