From what the jl site says 2 12w6 would need 25 cu ft and a w7 will need 18 cu ft so that is fine According to the JL site the 13w6 moves 69% more air than the 12w6 and the 13w7 moves 39% more air than the 12w7 Yes 69% is a lot but it isn't 100% so it isn't as good as 2 12w6
