Megatons for my kick section

Hi all I'm building the megaton em15 for my upper bass section the plan calls for eminence kappa 15lf but I already have the kappa 15A drivers that eminence states are midbass or upper bass drivers so surely I would be better to use them if I'm sitting them on top of my void loaded X1's? Any ideas? Or should I sell the kappas I have got and get the LF versions?

I would do that with normal kappas. But make sure you don't go past not so great excursion limit of these. That's "the problem".