Micah, now that you know how to install the drivers and amps on a sub, you should take advantage of the JL sale on W7 subs. For about $900 (each) you could order two W7 drivers, the same drivers used in the Gotham and Fathom, and $700 for a Class-D mono amp. Build a fiberglass box real quick in the garage, and it would sound just like a Gotham 213! Well, probably close anyway.
Panny 3000 PJ, 118" Carada, Denon 3300, PS3, Axiom QS8, PSB 5T, B&W sub, levitating speaker wire