Cool project, i'd be interested in some pics later! I have some questions if dont mind.
As far as sound deadening goes, are you going with dynamat? If so, they have tons of versions of dynamat which one did you go with? How much did the sheets cost?
What amp are you pairing with the sub? (or perhaps i missed that in your post, then nvm lol)
What car is it going in? Ive yet to see a single sub in the trunk of a subie, and i was curious of how much room would be taken up. I may be going with custom or pre made box later. Is it a 10 inch sub?