Very true about MDF, has a bit more boom than the sound of fiberglass. I made that comment just because of the weight and it looked out of place next to all of this
VERY IMPRESSIVE fab work

. Then again I managed to fit a 1" MDF box for 2 sealed 12's entirely underneath the package tray of my '72 Nova... it's big & heavy and needs to go away.
EDIT: The torx-head socket screws are a very nice touch and something that people either won't see or won't notice, but goes to show the
AWESOME (!!!) attention to detail that this build exemplifies. Keep up the fantastic work!