amplifier, subwoofer turn off pop

Ok, I am going to outline this the best I can. I have done some searching and I don't see quite the same issue I am having.

I have a Kenwood DNX-7100 Nav hooked to a Rockford P1000-BD amp powering 3 Pioneer Premier 10" shallow mount subs.

When I do any of the following I get a pop/thump from the subwoofers:

Turn off the Radio
Change Radio Station/CD tracks.
Turn on the radio.

Now the interesting thing was I rested my hand on one of the subs when it was going this and it was almost like for the split second the polarity on the sub was reversed and it was pulled in ever so slightly and then when the next track started it released and worked fine again.

a Possible gain mismatch comes to mind, grounds seem to be ok, I have it under a seatbelt bolt and I cleared away all the paint.

Any thoughts I never noticed it until today and it is quite perplexing.

Sounds a lot like a bad ground on the RCA cables. I did read your post and I know you do not have a Pioneer deck, but it sounds a lot like their common problem.   You can check this several ways, the easiest will be to remove all RCA cables from your amps. Place them somewhere that the outer part of the cables is not touching ground. Then take an ohm meter, set it to the ohm scale, ground the black lead and touch the red lead to the shield of the patch cord that is normally plugged into the sub amp. Let me know what kind of a reading you get.

It could also be a problem with the mute circuitry in the deck.

well a quick update as I have not been able to do your test yet. I disconnected the RCA's from the sub amp and the pop/thump went away. Upon further testing it does not thump when changing CD tracks, only radio stations.

I'm going to take some readings on that grounding jacket tomorrow, what should I be looking for.