with that large of a room, the pressure vessel gain effects won't be kicking in until down in the low teens.
"booming" won't come out of a well designed sub, ported or sealed. booming is usually a function of the room. rooms have "modes" which are natural frequencies where they combine to make big peaks or big suckouts in the frequency response. big peaks are often accompanied by a slow decay rate in time. that is really where most of the "mud" comes from in bass.
by putting a second sub in a different location, those peaks and dips can often be smoothed out quite a bit, hence the suggestion above for two indivual subs if that is possible.
also, paradigm cheats on specs like nobody i've seen and i've owned them so i'm not a hater, just saying. don't use their specs to compare with anything that you see posted here. very few cheaters here.
just to provide some sense of comparisons, i've added my best guess for the paradigm sub (purple) that you have to the two uls designs already discussed and threw in a "go big" option--two eight cubic foot ported enclosures tuned to 16hz that each house a jbl w15gti sub (they go for a little over $300 here) (orange). these responses are naked, and the orange, red, and purple will all require a steeper rolloff than is shown.
the w15gti is a super clean sub btw.