I just picked up a set of used mtx 12" blue thunder subs for my car. Only one problem, the box is to big and the only way they fit in my trunk is if they sit right at the back, taking up all of my cargo space. I want to make a new box for them and i dont know if this box is the right volume so can anyone tell me where to look for the ideal enclosure volume for my subs, thanks. ps. the mtx site was useless for finding the info.