I am building a vented sub box for a 12in BTL thats Fully loaded.. it is going into a 2005 Honda Civic... right now I have the Height as 15inches, the width at 32inches and the depth at 13inches.. it comes out to 2.70 cubes I am tryin to figure out the Port size and length for the box to have it tuned to 32hz if anyone could help me I would greatly appreciate it.