Rsd box size

[ferrariboy150]

Im about to recieve my 2 rsd's in the mail and wanted to get started on them i have been reading around this forum and it seems like 3.6 cu ft is what im aiming for. my question is how many inches around the sub do i need to leave for instance, whats the minimum height it can be since the subs will be 12 is 14 too small?