I never guess to put more power to a sub than they are rated for. I say a sub can play ín a bigger box with lesser watt´s to your satisfaction, and if you build a smaller box you have to give more power to control the sub.
PS Sorry that was a little bit less,
we have a member here who have 2 DC lvl 5 each on little under 1000 watt´s each, and he play over 150.
Idk know your subs and there specs, im from Europe and in the moment no MTX distribution in Europe and i never
heard of Punch Z subs (could be that is RF line but idk).
I would do the 2 12´s only the MTX is the real better sub i would do the MTX. Steps of quality, better sourounds, bigger coils,
more cooling, better cones and so on. At my last carshow i saw a vew of cruel and cheap subs, who´s never get low with
washy sound, but them was loud for less and the noobs didn´t hear the diffrence and saw only the price.