Audio Question

Whats up guys, i have an 06 sentra SE and i was just wondering... how would i do this:

I want to install a kicker amp(1000 watt max), w/ 2 JL 12" subs.
How can i do this installation since there's a 9" sub that came w/ the car? Can i keep it? and have 3 subs? or would i need to get rid of it?

Will the battery that i have now be able to handle the new subs?

Thanks.

see my post about installing subs and amp......ill link you or you can search for "installing subs"