you're already on the small side with the power you have, especially with the alum coils.
Personally unless you plan to up the power I'd go bigger like 4.25-4.5 per sub.
I'm running 4 in 18cubes in a wall with 360^2 of port area, but drop it down to 288^2 @ 36Hz for daily. Did 154.2 with the daily tune and 154.5 with the higher tune, both legal on music.
I still plan to switch to the new coppers after the CACO show...