Caps are a waste of money. You are better off spending about $20 on upgrading the Big-3. Don't listen to the marketing hype of "stiffens your bass response". It doesn't. It filters your power line going to the amplifier keeping the peaks low and the valleys high. Also, if your alternator cannot handle the extra charging source they will turn out to be a big headache even more so than you think. Don't buy a cap... upgrade your Big-3 (see the uber fine sticky in the wiring forum). If your lights are still dimming, upgrade your battery and alternator. If your lights are still dimming then, you have a serious problem. Adding a cap to your system is nothing more than a band-aid to a bigger problem.