Help building sub box

[chubalicious]

Ok guys i know this question has popped up alot on here but i need your guys help. I am building myself another custom box and i want to do this one right and to specs and loud as hell. Ok so here we go. I have a honda civic coupe and what i did was ripped out the rear seats and i am gonna seal off the trunk completely for smaller air space in the car. I am having the subs face forward and the port as well. I am using the sheet to block off the trunk as well as my front face of the box. the rest of the box will be inside the trunk. I have 2 dc audio lvl 4 12's and the box needs to be 3 cubic feet just for the subs themselves. Ok how do I design the port and what should i have it tuned to for the best and loudest sound? I also need help doing all the numbers including port and subs to make sure the subs truely have 3 cubic feet for themselves. My goal is 150db+ and i want to reach it on these subs. Also do i have the port on top or bottom for maximum sound? I want to do comps with my setup as well as daily bump. I know i just asked alot but guys please help. I want the best box and to come out nice. Thanks guys...