Well it would depend on how much power you have which will help you find out how much port area you should have and will it take up any of that 10 cubes with 1cube in sub motors + the port? 10/4 is only 2.5 each. That is too small,4 12's would be fit well but if the dd's can do well in 4-5 each do them instead. I think 3.5-4 is good for a 15 R with 50in of port area and 1500RMS 2000burps. 12's like 2.3-2.6ft with 40-50in of port area depending on power, tune 32-37 per vehicle. Figure out what kind of box you plan with the two DD's and see if anything else works out.