My son is looking at buying a DCON-12 S4 for his car. He will have a Alpine MRP-M500 pushing the DCON. We want to build a ported box for the DCON. SSA says optimal ported box is 2.25 cu.ft tuned to 28-33 hz. I tried downloading the box design from SSA. I can get the google sketch picture, but not the other file. Can someone help me with the box dimensions?