[Bondonutz]

I'm no guru but I learned a lot when I installed my first real high end system.

To port or not to port;
A unported sub box will not need as much power to be driven as a ported box so depending on the RMS capabilitys of the Amp this is going to help decide.
A unported box will have a much tigher bass sound than a ported box as well so what your bass expectations are will dictate also.

I had a professional build a unported box for my Jeep because I didn't want a huge speaker box taking up all the room in the back, I'm really glad I went this route because it sounds incredible. The sound of a unported box is way more universal if you listen to a wide variety of music, if you want lots of bass then ported is what you may want.