American bass HD 12 box build!

[bkoster283]

im trying to figure out exactly what woudl be my best bet im running a american bass HD 12 on a American bass VFL 120.1. my max is height 20, width 50, and depth 36. i couldnt really find any recomendations on a box for the specific sub so was thinking something like 3 cubes tuned at 35hz. i have been messing around with torres and came out with 17 height, 25 width, and 17 depth. with 1 port 6 in diameter and 16 length and i came out 2.99 cubes @ 35hz. this is my first box build ever and am a little skeptical about it all any advice or tips would be well appreciated. its all going in a trunk of a civic so another question would be subs up port side, or subs up port back etc.. link below is for specs on the sub..thx in advance

http://www.americanbassusa.com/product.detail/product_id/40