This is my personall opinion; no matter what you run from the battery which is in the front, to you amp in the back, of it pulls enough, lights will dimm. The reason is the fact that the alternotor has a "turn-around time" if you will. When the bass hits, it draws a substantial amount of power, but not long enough for the alt. to pick up the lag. That is why a cap is not so much a bandaid but a float device for the system. You keep it as close to the amp as you can so when pulsed-power is pulled, it pulls from the cap.
1997 Black Bonneville SE/SC - Scarlet - It'* fookin FAST! My dad spanked a Honda with it, and he dosn't know how to drive fast
1997 White Bonneville SSEi - Cheetah - The wanna be cop-car. Just rolled 203,080