I cant seem to figure anything out when I put in my specs on winisd. If you could help me with this I would greatly appreciate it. I am using TWO earthquake balls12 dvc , The measurements of the box are 31" wide , 15" tall , 18" deep . I can go smaller but not any larger with those measurements. I have been told many times to use a vented box with these , so I prefer to use rectangular ports . If you could tell me where to locate the ports in the box would also be helpful. Thanks for any help!