I have pretty much the setup you said you're going to have...lights, and stereo, even an e-fan and I have been running with the stock alternator for over 2 years and have NO PROBLEMS!!!! I have a yellowtop and 5farad capacitor, the capcitor didn't help much, it did help a MINOR part in dimming lights. I also have the big 3 done along with a couple other wire upgrades.
About the stereo system. It depends on what quality you're using and types of amps. If you're using a class D for the sub(s) it will draw alot less amperage than an a/b. I have a Soundstream 800rms class a/b and it draws 130A max. My friend (rudeman85) has a 1600rms Hifonics amp which draws the same or a little less than mine!
I recommend getting a HighOutput alternator before a capacitor if you have any large voltage problems.
Last edited by rideac1; 11-16-2006 at 09:34 AM.