Re: 12" DC's box build for F150.
I post over @ F150online.com sometimes and sounds like you've been through a few different setups already.
Have you tried a ported setup yet? With the space you have available I think a single 12 in ~2ft^3 tuned in the low 30s would work perfect. You'd have as much output as two 12s sealed, maybe perceivable more since you'll have better low-end response.
'10 F150 - 3Sixty.2 / MTX 2150x / MTX 275x / Blueprint XBL^2 Subs/ Boston SL80
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