The 12 will produce a lower frequency sound since its surface area is larger and can move more air. I would focus on the box now and pick the sub based on that. Ported would be your best bet for the high SPL so design one for your trunk for each sub and see what is going to turn out best. Let the whole system help you decide.
BTW I have a type R and love it, it can handle the power of a big amp, just don't throw a m1000 on 1 type r and play it loud for 4 straight hours or it will give out in a few months. 2 fixed that issue.