sub amp combo

Hello All, Looking to install a sub (or two) in my car (have 4-4.5 cubic feet). Limited by height of trunk opening. It's a 2013 Mustang coupe so I think max height of box is like 11 inches (39x22.5x11), unless someone with a 2011-2014 coupe has been able to fit a bigger/taller box. edit :- was...