I've got 2 x 18in BL's going into a wall and was wondering how big to make the port. The way it sits now, there's about 10.5 cu per sub. How much port/port area should i have. It is for daily booming and bass race.

~150 sq in.

We recommend 12-16 sqin of port per cuft of enclousre. But there comes a point when enclosures get that large that 300sqin of port for 21cuft is just dumb for a daily driver and you probably wouldnt notice a difference between that and say 200. But... as it is rather large as well, having 200sqin of port is still only 12" long (before any sort of end correction if it is not free standing).

*hits self* Thought you said 10 cubes overall...

In that case I agree that 200+ sq in. would work well.

it looks like after displacement we're shooting for 8 cu. a sub, with about 200 sq in of port....what do you guys think?