will reversing polarity on sub damage it?

I just recieved a 8" Clarion 75w RMS subwoofer, I had JUST figured out today (Just found out about the AA battery trick pushing cone outwards for correct setting, after having played on it for about 10 hours total) that this subwoofer had been set up WRONG in the box.. IE, the + was put on the - of the sub, and the - was put on the + of the sub..  I tested it with a little AA battery, and the cone went INWARDS, meaning the polarity was messed.. fixed it and thought to myself wow I finally figured out WHY this system pounds soo poorly and very quietly.. I have a rockford fosgate 500.2 amp, with a jvc deck that supposidly puts out 4 volts.. I swapped the deck out, and rca too, and nothing has improved the poor bass in the car.  Fixing the polarity fixed the quality of the bass, however.. It is still soo very quiet.  Only time when the bass improves, is when I turn the speaker volume up to full to when the speakers start to distort on some bass notes and even then it is still not that very loud.

I am trying to figure out, if running reverse polaritys might have buggered up this subwoofer?  I do not know how long it has been reversed in polarity for, it was given to me all setup like that, so I do believe there is a chance this sub might have seen a couple hundred hours of play time in reverse polarity?   Would having played the sub in the wrong polarity for this long possibly damage the driver/speaker?  Or is there another problem in the setup somewhere? 

I'm pretty much a newbie, but AFAIK, it's a practice to do reverse polarity when your sub is out of phase, there are HU's and Xovers that allow you to change/reverse polarity/phase without touching the wires. This is done when the sub seems to lag from the other speakers.

As for the loudness, I'm just guessing, but I don't think you can expect too much from 75Wrms. How "not loud" are we talking about? Could be that or poor box design or wrong position. How is it setup (ported, sealed), box size, SVC/DVC, position in the trunk (facing cabin or rear), etc.? These details can help the gurus to give us the answer :).

No having it wired backwards will not damage it. As an example people doi it all the time in compound isobaric configurations.

David

I've already done all that, swapped the deck out with another deck of the same model.  Swapped the amp out, same symptoms, I made sure the LPF were on the deck + amp, the gain is set almost at full and still the response is very weak its almost like the voltage coming out of the deck is minimal.  It is in a bazooka tube, really primitive however the original stock sub that came with the tube was replaced with a better 8" Clarion subwoofer.  The bass really should be better, I know for a fact that it's really too low.  I mean it really barely bumps.

What would the result of using one crossver on HU, and one on amp?

The thing is, with the head-unit, in the section where i adjust the sub-volume, there is a setting I have to select, either low, mid, high.  there is no "full" selection, so i cannot bypass the crossover on this HU.  So I take it, if I should make a change, it would be having to change the crossover on my amplifier to "full" ? It is currently at LPF