Help on first box build

[lovinsomebass]

I am building my first sub box and needed some help with the port measurements. the box is 28" wide, 22" front to back and 18" tall. I was wondering if a port would be better up the side or along the bottom and what a good size would be for it because I can get 34hz with alot of different combinations on Torres calculator. Its a 2200rms psi 15 in a trailblazer and wanting sub up port back. The box is showing 4.78 ft^3 before the port but should it be bigger? Thanks for the help guys.