Most people at Best buy have no idea. That being said, yes ported is usually considerably louder. I wouldn't go with the prefab boxes from the site you listed because those boxes aren't made with your specific sub in mind. They are made to try to accommodate a large variety of subs and its usually not very good. You'll be much better off building your own or having someone else build you a custom box. There are several skilled box designers on here that would probably be more than happy to design you some box plans. may cost a little more but it will be completely worth it in the end.