Your lights didn't dim as much because you added a ground. Capacitors only discharge once voltage has dropped below ~12.6V. A 1 farad capacitor can only support an audio system that presumes "1000 watts" for a fraction of a second. After that, it becomes an additional load but it only charges once the system is above ~12.6V. Caps are worthless because a well built power supply in your amplifier has exactly what it needs to support it's function.
http://www.grandprixforums.net/upgra...tml#post298578
Btw, you can buy a few 1 farad caps for a few bucks + shipping. You don't get the ginormous pretty cases that companies like Rockford Fosgate might give you but I guess that makes it more manageable too? It's your money to throw away...
http://www.mcmelectronics.com/produc...LAID=220396964
