help with zapco amps and subs?

hi, i am just installing a new system with zapco amps. now i have chosen to go for the c2k 4.0x for the front and rear comps. they will either be DLS iridiums or MBquart premium series components. which comps would be better.

For the sub is where i am confused. Firsly, i have a choice of going for the Zapco c2k 6.0x which is well within my budget. it puts out 1200x1 at 2 ohms. will this be enough to power a sub like RE xxx 15 or the jl audio 12w7 (which is a better sub). or should i go for the c2k 9.0x with 2000x1 at 2ohms bridged or 2000x1 at 4ohm bridged. this would be slightly out of my budget so if the 6.0x wrks then its great.The orion 2500d is another choice.

Also, since my amp is at 2ohms bridged, do i need to get a sub that is dual at 4ohms like re xxx's offered or a standard dual at 2ohm sub will be fine. The JL w7 is at 3 ohm i think.

We already had this discussion about the XXX and W7. If you get the 2000 watt amp that will be a bit much for either sub. The W7 isnt that a dual 3 ohm sub? making a 1.5 ohm load? which really is a 2 ohm nominal load, I think so I think it will work on that zapco amp.