I bought an fi btl amd box before (18) and was planning on upgrading the sub to a sundown z v.4, but dont really know much about size of box or even the htz its tuned to, would it be the best to build a box designed for the sub, probably lol, but what I would like to do is see if the box I already have would be a good fit or just upgrade the box altogether, does anyone know the demisions on what a sundown z v.4 best uses, to see how close it is or if I need to go build one