hey. i have a 400 watt rms amp pushing a 400 watt rms sub and my lights would dim alot. after i put a 1.2 farad capacitor to it, the dimming went down alot but there is still a little dimming occuring. i have my amp mounted inside of a plexiglass box with a neon inside and the neon dims and it looks stupid. the neon gets power from the remote wire and is grounded to the body of the car. any suggestions on whats going on? do i need a new battery or alternator?!

 

both get a optima deep cycle yellow top battery and a higher amps on the alternator?!

 

You should not be having dimming problems with just a 400W amp. It looks like you have other electrical problems. I would start by checking the alternator, my guess is that it went bad.