I have two 3002D4 's and I'd like a 2.5ft^3 net @35hz. Factory specs call for 1.2ft^3 per sub in an enclosed container. The displacement of the subs are .181ft^3 each. I'd love to be able to do the math but I get lost when figuring out the port volume. Any help or suggestions would be greatly appreciated. I would buy a premade box if I could find one to specs.