I'm working on the plans for building my first box, and have some basic questions that I'm hoping to get help with. I'm thinking about going 2 chambers with 2.5 ft^3 each, ported and tuned to 33Hz. My questions are, when calculating the port size, does the height / width matter, or do I just pick them semi-arbitrarily based on the cross sectional area that I need? Like, would I get different results from a 3"x12" port as from a 4"x9" port, for example (both 36 in^2 area)? Also, I wanted to make sure that I'm using the right numbers to calculate the port length, I use Vbox - Vsub - Vport right? So do I calculate this as if the box is 2.5 ft^3 and then actually make the box slightly bigger to compensate for the extra volume added by the port? I don't have specific dimensions to work with yet because I've been a little bit confused trying to figure out these formulas, but I can try to come up with some if it would help to get my questions answered.

Any advice that people have with regards to these planned specs would be appreciated as well. I'm sure most people here have more experience than me with regards to building sub boxes.