WMD18 box preferences

Ok i just bought an 18" WMD from Pierce Audio and now i want to put it in a ported box but I just cant decide on what size to build the box. Some help with ft3 would be nice i want a ported box i will build it on my own becasue all my other boxes have sounded great. i think i have a gift in box building //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif but ya just maybe someone that owns one and found the right size to slap the lows with this bad boy could help me. thanks

Tom