I think your sub box needs more height/depth and more air space. Looks like your sub is jàm-packed in there looking at your third pic. I personally haven't seen a box like that.Here are some preliminary pics.
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Installed threaded inserts into the box.
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Didn't have a table saw saw so the cuts weren't the best on this end. I went back and sanded it really flat.
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Test fitting the amp in the new glove box.
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