Okay, as far as your post...there is no ground on the other terminal of my optima battery. I can only see the power cable going to the + red terminal but there is nothing else on the battery.

I found another site with some of the same information you had: http://www.mmxpress.com/technical/noise.htm

The thing is...I am preety much screwed because this business is refusing to do any more work and they are saying that all the engine noise is due to the head unit. This does not seem right though since I have two head units in my two din dash and when I am just running the other head unit for cd/dvd etc I still get engine noise which leads me to believe that it may be something else (but not sure since the two head units are connected in the back). THe installer told me that he tried another amp and there was still engine noise using a totally different amp.