I've built boxes for at least 15 years. But, i've never built a ported box like this. This box is gonna be 31.18 cubic ft 52 in wide x 37 in tall x 28 in deep. Trying to figure out how to fit all the subs and where to put the port. My guesstimations on the port size would be 15 in x 20 in and port length would be 8.13394050 ??????????I put the width and height in on a port calculator and it comes up with this length. What is that? I don't understand the length part. Don't even know if I can make a port hole that size with those subs in there. I was thinking of slotting the port either at top and bottom or on the sides. Sides would be better i'd have more room. I've never built a box like this so i'm clueless. Always built sealed boxes. Please help.