Memphis recommends a 1 Farad cap per 750rms watts of amplifier power. 1f per 1000w is ok.
http://www.memphiscaraudio.com/LiveImages/114/44/DocumentURL.pdf
I would recommend running 2ga wire. You wont be able to turn this up unless the car is running… I believe the stock alternator is a 80amp unit. To run this system you need at least a 160amp one.
Understand that your battery does not power your system. Your alternator does. If lights dim when the bass hits that means the alternator cannot supply the power demand of the amp and electrical system combined.
You need to get a custom alternator to run this system. Thats not a suggestion but a fact. If you do this without then not only will your lights dim but the ignition will drop out and the car will run like shit when you have the beats cranked up.
This will most likely fry the existing alternator as well.