I just built a fiberglass box for 2 12 w7. It fits nicely in the car but in order for it to look how i wanted i had to make the box bigger than the recomended specs..
Its a sealed enclosure. Kind of makes a hollow noise some times. Like the box is too big. I have like 2 yards of fleece left over which i think will make a good insulator inside the box.
I was wondering if that the fleece counts as a displacement to make the volume in side the box smaller.