If you have to ask, I wouldn't attempt it. Running two of those subs is a real task. Do you have any idea how much power you'll need to properly push two xxx 15's? Do you realize the box size you'll need? Do you realize the extensive charging system upgrades it will require? Going into a project of this size, asking such basic questions as you are here, makes me skeptical you've realistically thought through those very real problems.
Im setting up a system with 2 of the older xxx's and Im running dual alts (260 amp dedicated), 2 Kinetik 2400 batts, dual runs of 2/0 cable run in conduit, etc etc. The new series XXX is grossly more power hungry than my subs, I cannot imagine running a pair unless you REALLY know what you are doing. Just buy the dub7's and have your local install them.