I am making a ported box for 2 12 inch subs. I everything calculated and most the measures but i dont have the box dimensions. It is a 2 chamber ported box with 1.6cu ft in each. The ports are round and are 3"x8" with 1 in each chamber. Can someone figure out the dimensions on the outside ( Im using 3/4" mdf). Also, are those ports ok. WinISD says it will be tuned to 29hz.