Phase 1

It's rare to see subs that are mechanically sealed only. The Earthquake SWS comes to mind. Most subs, according to T/S and looking at the database in BassBox Pro will work the same in either or but ported naturally has loudness advantages. Unless one is more sensitive than the other, even the Sundown SD's or old school Solobaric's get louder in ported and they were intended for sealed. Also, what about the f3 of the car? I think you're putting too much importance on that particular T/S parameter. The choice of sub is only important to the mechanical aspects of what you are wanting. 90% of your output is your box design assuming the rest of your install is on point. You can build a box to make most any sub sound how you want. Cabin gain plays a huge role as well. You have the F3 of the enclosure which is outside, having no relevance once inside your car. Vehicles act like a mechanical EQ, which is why the same system can sound so much different between truck, sedan, hatch..etc. Just focus on the sub that provides the mechanical aspects you are looking for and build a box around it. Simulate it in software using your vehicles acoustics. You can tell a lot about a subwoofer just by it's suspension compliance which should loosen up once it's completely broke in. A sub that doesn't have a very linear compliance after break in, won't perform as effectively in the lowest frequency ranges. Once in a car, you can have a relatively high F3 point for the enclosure yet still have in car response flat to 20hz because the 12 db (give or take) of the vehicle counter acts the drop in output.