the light dimming is essentially caused by the difference in voltage between the battery and the alternator. Alternator is about 14 volts battery is 12 volts...so all electronics run @ 14 volts when the car is running, but when you consume all the current the alternator has to offer then if falls back on the battery which has plenty of reserve power, but at a lower voltage so you get light dimming on hard bass notes (notice your lights do not dim as bad with the car off?)... Caps don't make power, but they do help buffer out the light dimming issues. If you simply don't have enough power than a bigger alternator is always better. But bigger alternators don't last nearly as long as the originals....More batteries will only give you longer reserve power for 'key off' listening time, when the car is running those batteries create an additional load on the alternator making your problems worse. Do not add more batteries to an over-taxed system.
