I needed some help on a box design as well as how many cubic feet will sound on 2 12" W7. JL Audio recommends 1.75 cubic feet so 3.5 for two. After displacement of 0.28 cubic feet total the box will be 3.22 cubic feet. I was thinking of going a little bit bigger and doing a 4.3cubic feet and after displacement it will be 4.02 cubic feet. Also what would you recommend the box be tuned to? I was thinking 34-35 hertz but I am not sure. Please let me know on how big or small I need the box as well as what it should be tuned to.