i just purchased a kicker zx 1000 watt mono amp from a friend
that runs 1000 watts at 2 ohms. and i was wanting to hook 1 12" L7 to it would i need a 4 ohm or a 2 ohm sub?

 

dual 4

 

dual 4 can be wired to a 2ohm output, and dual 2 can be wired to a 4 ohm output. those are the common configurations, but there are MANY more possibilities.
here is a good calculator to use:
http://www.rockfordfosgate.com/rftech/woofer_wizard.asp

you can use it to find out a variety of combinations with different numbers of subs and resistance.

 

Thanks for that calculator Paperboy... It Explains alot