i need help with box design

[soundstream15]

i have 2 12 sundown sa running of audioque 1200d and i got someone to build me a box but i wanna get some input for a good design or what i need to have, my max dimension are 34w 16h and 19d i dont know how much air space the sa's need so let me know what you come up with. i dont need a full design i just wanna know what cu feet i need for my dimensions

[soundstream15]

?

[StreetMetalBen]

http://www.sundownaudio.com/index.php/products/subwoofers/item/sa-series.html?category_id=2

1.5-2 Cubes per 12