Which Sub to get?
 

I have a JL 500/1 amp which plays from 1.5ohm to 4ohm no problem.

Would a Alpine Type R 2ohm/2ohm be better than a 4ohm/4ohm?

What should I get? I am a fan of SQ.

An amp will get hotter with a lower ohm rating, ex 1ohm hotter then 2 but the JL runs the same power at any impedence so i would recommend getting a Type R dual 2 ohm to run it at four ohms on the amp.

yeah I agree with ^^, if your amp gives equal power at 4 ohms, then get the dual 2ohm and wire them for a 4ohm load.

Agreed^