if you are adding big loads or long runs, please consider upgrading the chassis to battery ground to 2ga...
another thing is that with many electronic devices like amplifiers and other metal cased devices the outside shell is ground. Avoid if possible screwing and in essence direct grounding them. For some reason they will give you noise if they are grounded thru the chassis instead of thru the ground wire.
mount them isolated, using a wood block or plastic to electically isolate the chassis from chassis.
Ever since i started doing this 8 years ago I have never had a single alternator whine problem in any install. Example, in my current car I have 2 ga power, changer cables speaker cables and 3 sets of rcas bundled together, and in my mgb after adding a bigger ground for the dual batteries, and isolating the amps and crossovers by building a trunk board all noise was eliminated, and that was a noisy little car to begin with.