i'm just curious if there is any programs for designing the actual enclosure. i have downloaded ones that require all this jazz about speaker and gives a graph.. but i just want one that gives box designs. i see peoples that have it so there is an interchangeable port and stuff how do you design that kind of stuff? i have just been using subwoofer tools for my sub boxes. both have turned out okay. even better is if someone could tell me what port area, port length has to do with the woofers. i just need some enlighting.