I have a 2004 Cadillac Seville SLS with a brand new OEM replacement battery. The Alt is stock and in good working order.

I have been running 2 12 inch Pioneers on around 600 watts for a few months and have had virtually no dimming or anything of that nature. I have simply ran 4 Gauge Audio Pipe ( I know crap wire ) with a fuse from my battery, located under the rear seat, to the amp, and 4 gauge wire from the ground on my amp to the cars unibody, where I have sanded the paint away and made a good solid connection.

I have recently purchased a Hifonics 1700 watt BRZ amp to push two Sundown sa-15's.

The sundown dealer that I purchased my subs off of told me that I will need to upgrade my wire, which I knew, I was just expecting to run quality zero gauge wire from my battery to the amp, and zero gauge from my amp to the chassis ground and call it a day.

He told me that if nothing else, I have to run another, at least 4 gauge wire to my alternator from my battery, and zero gauge from my battery to the stock chassis ground. As well as the zero gauge from the battery to the amp and the amp to the ground.

Has anyone done this upgrade on a similar gm car? where the battery is under the seat? Also does anyone sell terminals that you allow you to unhook the factory positive and negative leads to the battery, add in a new lead and bolt the stock one back in, or will I have to cut my factory wires and attach them to a new terminal along with the zero gauge run for the amp and the 4 gauge for the alt?

I am okay with my lights dimming if I am really pushing the system, I just do not want to harm my car, and would like to be as easy on the amp as possible.

I have been told also that the stock alternator will be fine, as long as the wires are upgraded and everything has a solid connection.