need help designing slot port box for 2 10" kicker comp vx subs

i would like to build a ported box for 2 10" kicker comp vx subs, the biggest i could go is 38" w X 16" h X 20" d, not sure what to tune it to and i would like the port in the center of the box. I listen to mostly heavy rock and metal and if some one could give me some measurements or a design that would be great! i'm pretty good at building boxes just havent messed with ported boxes much, thanks

I post in your other thread, but I do $1 designs.

^^this

@ buck sounds good, how can i get the $1 to you?