Good shallow-mount sub?

[DFA]

Went to take a look at the RF today, the thing sounds great, has a couple of dings on the outer (decorative) metal rim, but it's nothing I can't live with (especially since I'll be putting this under the spare tire cover).
I'm really happy with how it sounds, took it off the guy's hands and brought it home, cleaned the dust off of it, then realized the box is crap, I'll go grab some 3/4" MDF and build me a better box a couple of weeks from now. The two coils wired in parallel have a beautiful impedance of 2.01ohm and the cone moves freely, so voice coils are in good shape.

Thanks everyone for the advice! especially goku for that sexy sexy chart. I beleive it's something you should share with everyone once it's ready.

Now, on to raking up some extra cash to get an amp to actually move this thing.