Just for kicks I ran those numbers in Torres and will ask you this... where did you come up with 4ft3 net?My first thoughts on the box 24 L x 20 W x 15 H which gives me a little bit over 4cuft3.
It seemed awfully small for 3 10s to me.
Once the subs, port and any other displacements are taken out it's going to be AWFULLY small.
I'm thinking you must have mistyped the sizing.