this is in general
1.75-1.9 cubes sealed per woofer
3:1 ratio
5.25-5.7 per woofer ported side
16-22 ippc
tuned to your cutoff point 50-65hz in most cases
but you should really do your own testing bp boxes arent a one and done deal you have to keep making small changes to them in order for them to work right