IRCC DD subs with composite cones have softer suspension ,at least mine does.I believe its because of lower moving mass,but they can handle the power,I think..I know they will hold 4k but they maybe able to take more,I just dont have that kinda of power to find out.Someone on here knows for sure.But u dont have enough power to do 2 18" solos,so u would have to do 12"s.They would get loud but wouldnt have the sq.I love my 9917,but I would love to do 2 15" Mags or 2 18" 05 RE XXXs,but for now I will stick to what works,I doubt I will be moving away from DD and Kicker subs anytime soon.dd9918? i could probly only run one of those..arent those power hungry? it would probly need both my 20.1's to wang.. 2 12" solo x's didnt think of those either... would they be louder than the DD's?