UPDATE: I think my new enclosure took a shit on me... I kept hearing this metallic flickering sound at high output from the subwoofer...

Did alot of work inside the box:

1. Re-sealed the box edges

2. Cut interior wiring shorter as to not have too much inside the box faffing about..

3. Covered the interior wiring with CCF from SDS to eliminate the bouncing inside the box.

Sound was still there on certain songs and full output...

Talked to Sir Lancelot who advised me to do some free-air testing. I was only able to do a few minutes at 50Hz, luckily no sounds but will do some more testing later on. Maybe to some 20-40Hz tones a little louder than I was with the 50Hz.... What else could I do to test for the sound? Is free-air basically the best and only way to test for it?

Thanks to Sir Lancelot for helping me out at 2am a few night ago and liljestrand as well.... Good fellas!

I think it's your box.

Get a new box then??? I don't know if it is worth the time trying to "fix" it or even finding the problem.... It's not an easy one.....

To bad you don't live on the east coast like in NC. I have lot's of boxes sealed and ported you could try and have.

You could build a small sealed or ported box on the cheap.

Personally I would build one of the ported boxes in the SSA tech sections and wake that sub up!

ARGHHHH!!!! But if I do that then I have to set SSF more accurately and I can't just bump irresponsibly.....

Kinda curious, have you tried playing the sub in the box outside of the vehicle?

No, but I don't have anything inside the trunk that I think could be making the noise... I also put my ear to the subwoofer and it def was coming from it or behind it....

Still not convinced, putting your ear up to a sub at high volume and being able to pinpoint where a sound is coming from, not going to buy that one. You could have created a new loose panel in the car. Also kinda find it odd to get a metallic sound from a wood enclosure.

Well the only thing I could say may be something I did now that you are referencing that... I used zipties to hold the CCF on the wiring inside the box... Maybe I'll use some nylon string since I've got everything out... If I free-air and def find the subwoofer not to be a problem, should I re-mount it in "new" screw mounts and fill the old ones in? I only ask because I noticed that just mounting the subwoofer twice has made the screws feel not so tight...