Enclosure Size and Power Questions

Is your amp 1 ohm stable?  That is the burning question. 

You either wire the coils in parallel like shown here, or your other option is a 6 ohm load.  It boils down to what the amp is capable of, and the power you take from the car has everything to do with how the subs are wired.

Note in the manual a big difference in enclosure volume between ported and sealed.  You would measure your available space to find out if you have the cubic feet of room needed.  After that, it's a matter of personal preference.

There are some prefab boxes that are suitable for sealed, but if you are going ported then you should have one custom-made.