Question about building my own sub box?

I have 2 10'' 1000 watt max subs, and a 2000watt max amp pushing them. I want to build a custom box that fits and looks good in my sunfire. I built my first box out of plywood, because I had it laying around. Not very impressed with the performance I get out of them in this box so.... I'm gonna go get some MDF board, but I didn't know how to calculate the interior dimensions of the box and subs so that I can get a deep powerful b kick. Any help would be greatly appreciated! Dave