I am getting installed tomorrow it will be done a JL 13w6v2 with a 500/1 amp for my sub and a 300/2 for my mid and highs. My question is if my headlights go dim with just a JL 12w0 should i get a better battery like a kinetic or red top or what? I was told by a JL representative that caps don't usually work and this kind of battery is the best thing you can do for the car. I have a 1992 325i BMW. Anything will help as soon as possible.
Batteries only power your system when the engine isn't running. The alternator supplies all power to your electrical system otherwise. If you find you're having problems with your headlights dimming(and staying dim w/o recovery) then the first thing you need to look into is a higher output alternator. After you have that taken care of then you can add caps and batteries to your heart's content. The batteries will help run your system when you're parked and caps may help transient response, but neither are a substitute for an adequate alternator. The best thing they do is help line your JL representative's pockets.