MFW-15 Measurements:
Cutout Diameter: 13 7/8"
Driver height at highest point: 7"
Driver height below mounting flange: 6 1/2"
Flange Thickness: 1/2"
Surround width: 13 7/8"
Drivers widest point: 15 1/8"
Magnet Width: 6 1/2"
Magnet Height: 2 1/4"
I've also seen the cutout diameter listed at 13 15/16". An extra 1/16" won't hurt.