Got a beast being built. ZCON 15, and I have narrowed down building the box to 4.25 net, sub top port back. I'm going to go with birch I believe. I'm getting some mixed feedback on port area. Do these subs respond well to the tried and true formula for 16" of port area per foot? Looked at GP screw and glue, really slick but birch is stupid expensive from them. I'm just going to build it myself.