I guess I'll throw my .10c in here, since I have plenty of experience with PR modeling and using them in a car as well. PR's can work very well in a car. While subwoofers have gotten pretty beastly in the last few years, so have passive radiators. Most good PR's have 30-40mm of xmax and you generally have 2x as much cone area in passives as you do speaker. Passives don't have the limitation of airspeed through the port and the boxes are MUCH smaller. The crazy excursion on these woofers with the high Bl means they can produce a lot of bass in small ported box, but need a BIG port do it. If he wants to do 25hz tuning, he can use passives and make a 3-4cubic foot box, or he can use a correctly sized port and end up with a 6 cubic foot box, with 2 feet being eaten up by the wide and very long port. That's the huge advantage of a passive, that and adjustable tuning. Nobody get's car boxes spot on first try, when adjusting tuning takes a few minutes (rear loaded passives or only a few seconds (front loaded passives) that's pretty sweet. I can tune my box between anywhere between 45hz and 15hz in a matter of seconds.
Now to address that 5200. Those T/S specs ARE correct, your looking at quite possibly the most overmotored sub in history. While it's EBP suggests a ported alignment, in this case, the specs are so far from most other woofers, it's misleading. The only way to NOT make a fart cannon box out of this thing is to use a sealed enclosure. Interestingly, ANY sealed enclosure. You can literally put this thing in a box just big enough to fit the magnet structure and not really effect it's low end output much. Go model it in a 6 cube sealed vs a 2cube sealed to see what I mean, it's just sooo low Q that it really doesn't matter, the motor force makes up the difference. Nothing ported you can build will not be peaky for this thing in a car, that's not what it was made for, in a car it's good for SPL and in a home, it can give you very low bass in a super small box with some EQ work applied.
Beyond all that, ported and PR alignments are the same thing, they are both using resonators, the only difference one uses air and one uses a speaker cone. The suspension acts as another order of a HPF, so it' rolls off just a hair faster (5th order vs 4th order) below tuning, but beyond that, they are the same. Unless of course your port isn't adequately sized, in which case the PR will outperform a port at higher levels. Out of what you've posted graphs for, I liked the the white graph on the first page, that was pretty flat response overall. I believe that's the SSA Zcon? I actually had my eye on the ssa dcon for PR use due to it's T/S. What you generally want to look for for a "good" candidate for PR boxes is something that will model well in a small ported enclosure, slowly falling response for flat in car response, that needs to be tuned very low to do that.. With a standard port, that's a PITA type of box as the port ends up eating up airspace, making your small box not so small. DCON fits the bill, apparently so does the XCON, which is good as their other lines didn't when I messed with it, never even bothered with the Zcon.
