A caps ability to help your system largely depends on the amps, and charging system. If you have a fully regulated amp like a JL /series, or Zapco, a cap won't help much because the amps make the same wattage regardless of system voltage (12v or 14+v) If you are using a loosely regulated amp like a Dls, or Orion (I think) then the cap provides an electrical buffer to ensure a constant supply voltage to the amp. In a car like a Honda that only has an 80 amp alternator, this can be beneficial in a high-watt setup that draws as much amperage as the alternator can supply. For the casual user a cap is not really nec, and niether is a second battery, usually the big 3 is enough, and the battery could be replaced w/a yellow top if needed. I like a cap in a Honda, because it helps with the headlights flickering as the A/C compressor kicks on at night, though without it, I have never seen my headlights dim with the bass hitting hard either, but I also don't have a high watt system in this car. To sum up, most people don't need a capacitor, though if you want to use one, I really feel there is nothing wrong with that.
