I have used the series Dayton Series II 15 and they work in the cab but don't go really low enough for me. They drop off dramatically below 40 hz in my room. Output is realistically down to the low 30's with room gain.
The HWK 15
Is clean and efficient though......

BTW, the whole "levitated a floor rug" thing is really just the bottom ports blowing air along the floor to a nearby object. ::) No magic here. Don't expect the HWK to be the end of your sub search but and introduction to being unhappy with the compromises made in most subwoofer designs and applications. When you start to really analyse what good bass performance is. You want to keep going and going.....
This forum is a great place for ideas. It has many knowledgeable people..... also many folks asking the right questions

Eventually the subwoofer becomes one with the room. Like a chamber within a chamber. Once you understand how the physics work (subs are a GREAT example of this) you can apply that to your situation. Many people build all kinds of
speakers with all kinds of results. I think building subs is easier with more allowance for error. Plus it's just really rewarding when something works right.