I have a very odd shaped box (basically 3 boxes together to make 1 bigger one). When done they will come out to about 2.2 cubes. I want to add an external port, but I only have 2"(max)x8"(max)x16" to work with. I'm trying to figure out what that will come to. I'm aiming in the 36-38Hz range. If not could you please help me out with how long the port would have to be (using 2"x8" for the opening) to acheve that range goal. Thank you for the help.