do I need a second ground?

I have an optima battery and I am going to change the location of where I connect my amps to the battery. My battery by default connects to the alternator with the sideposts and what i am planning on doing is putting a platinum terminal on the positive top post and hook my amps to it. I am wondering if its necessary (or would benefit me) to run a ground from the negative top post to the same grounding point as the side posts. I thinking of running  a 4-gauge secondary ground. Thanks for any info!

Can't hurt any thing to add a second ground, in fact it will be beneficial. I'd recommend using a different grounding point from the stock point. Like scraping some paint off the frame some where (closer the better).

I put a new ground on my battery...about 6 inches of the new sweet kicker wire and the voltage doesn't drop as low and lights hardly dim.

using a second grounding point wont cause a ground loop will it?

Shouldn't

Well, I went ahead and did it with the second ground about 4 inches long and it seems to have really helped out the system. Thanks for the replies

whatt is a ground loop?

I'd say replace the 8ga ground with 4ga ground. Normally you should have same gauge power and ground wires.