Chassis or battery ground?

I recently read through my PPI amp manuel because I'm having some engine noise and EMI problems. Anyways, the manual says to run a ground wire the same guage as the power wire directly to the battery following the same path as the power wire. I always thought that this was a bad idea and that it would actually cause more of a noise problem. Any thoughts before I spend $$$ on more 4-guage cable???

its a bad idea to have your rcas run next to power wires. Check the resistance of all of your grounds.

Going back to the battery is a bad idea.

Im going to try this again because this site likes to kill my posts whiile refreshing. Anyways, I have a 8ga and a 4ga ground going from my amps in the trunk to my battery in the trunk. My battery has a 1/0ga ground about 18" long directly to the unibody. I dont have any problems at all. Why is it a bad idea? If you can find your info in your book, austincustoms, that would be awesome.

Well, I can't find anything, and the more I think about it, the less it makes sense.  Just to check, have you done all the obvious?  Upgrade the big 3, make sure your power is seperate from your signal, check the resistance on your ground etc.  If you've done all that, try running your RCA's down the other side of the car.  I've found that one side of the car can sometimes be nosier than the other, especially with the battery in the trunk. 

a few thoughts: If a trunk mounted factory battery is the closest grounding point, this is a bad thing??? Boats of course must have power and ground run to each point. Never heard of there being a problem. It costs more, more labor, but the results would be the same as if you had a chassis ground. As long as the wire guage is correct. Some vehicles now don't have a ridgid frame as we once knew, this might require you to ground at the battery. If you do have a standard frame, there is enough steel to still be very conductive for grounding. If you are picking up EMI off your power wire, Sleeve it in copper braid and ground the end closest to the battery end. Some ideas: Check your alternator. It might be throwing out contaminated power, bad diode maybe. Check your deck grounds. if you have a Pioneer deck, they are know for fried signal trace grounds. Use quality RCA's and cables. Make sure none of your speakers are grounding out. This can cause noise but not active protection circuits.

I just read in a car stereo instruction book that if you run a ground to the battery  that you can run the rca's inbetween the power and ground wires and that it will have the lowest noise interference of anywhere else in the car. Has anyone tried or heard of this before? Also, how do you check the resistance of a ground?