2003 FOrd Explorer Eddie bauer - Factory Premium radio with factorysub.
In a effort to improve bass I experimented with swapping the factory 6.5
inch sub with a JL audio 8" inch 8w3v2 (It fits with a 3/4 inch spacer
ring) . Tha factory box is between .4 and .6 cubic feet so the space should
work. I am using a alpine 450 w mon sub amp to run it.
It was muffled and farty (for ant of a bettter word) It was very obvious
the plastic sub enclosre flexed badly.

I layed 4 coats of fiberglass over it to try and stiffen it. The bass has
tightened up, but now the box has developed a horrible resonance that
overrides everythig else.. It literally resonates like the body of Cello
(the musical instrument). Run a orbital sander over it and it is like
running the bow across the strings of the Cello. Install the sub and
speaking voices of the DJ's now resonate so loudly in the truck you have to
crank the bass way down.

Any Ideas how to change that? I want to keep the factory sub mount ing
location as I need my cargo space. Unfortunately I have Rear Air
conditioning so the JL audio Stealth box will not work.