trying to find louder box for my 12s

hello, i was looking for a new box that would make my subs sound louder based off of a custom box, not the pre-built one that they came with. i have two skar evl 12s rated for 1250rms each and  just need an idea of what dimensions would make it the loudest. looking for either one with subs mounted on the top and port facing the front or subs on the front and port on the front (whichever one is louder. i am asking for help because i have never built a box before and need some help. i do know some dimensions i just need to figure out what the layout of the box needs to be. thanks