New Box for Two 12's!

[liteblue]

I am in the planning process for a new enclosure. My current box houses a single 15 and is the biggest box that would fit in the trunk 16 x 34 x 25. 2.5 inch baffle .75 everywhere else. There is barely enough room for amplifiers and batteries and what not.

 

For the new subs the manufacture recommends the box be 2.5 cubes and 40 inches^2 of port area. I am unsure about how much port area I need for two subs. Is it still 40 or double it for 80? I assume this is for square ports and not aero but am not sure.

 

New box plan: 16 Height x 34 Width x 21 Depth. 3 inch baffle, 1.5 inch back, .75 top, bottom, sides and port. Some 1.5 inch dowels for support. Square port, facing same direction as the subs, at 14.5 H x 4.125 W x 42 L tuned ~34 Hz with around 60 inches^2 for port area. Bass Box says after displacement I am only at ~3 feet^3.

 

I have built a few boxes but am no expert. Goal is to have it ready for Slamology in June. Subs wont be ready for about a month I am told so plenty of time to make adjustments.

 

What are some tips and tricks you have learned from building boxes? Do you think I should do something differently?? Am I leaving performance on the table with a box too small? Am I better off with less port and more net volume? Should I ditch the 1.5 inch back and just use .75? Any input is well appreciated.