If you see a lot of electrical problems people ask about, a majority of them are usually resolved due to a bad ground. Having more gorunds can only help eliminate some of these issues.I've had Gary's 1/0 battery cable kit for years now and never had any kind of electrical issues, for how often I drive the car it's probably not worth doing much past that, but has anyone with the kit done a few extra grounds? I only ask cause the kit I had on my TBSS had about 4 extra grounds, I'm wondering if it would be a good idea to use some of the spare 4 gauge wiring I have lying around and go from the battery to engine bolt down to the frame.
Grounding seems like one of those things a lot of people overlook, as stupid as it sounds I swear on the cars I've done this to they idle smoother (could be placebo) and I don't run into any dimming even with a large sub amp. Currently doing this to my TL, found a few premade Grote 1 gauge cables that were dirt cheap and should work well.
Additional grounds like the Frame to the Body is not common but a lot of people do it. I would say the more accesories or aftermarket items you add, like stereo's, amps and such, you can benefit from better grounding of the entire car. Heck, a stock vehicle could probably benefit from better/more ground locations.
Just be sure that in any areas where there is movement, like the Engine to the Frame or Body, you use some flexible grounding cable to allow for Drivetrain movement. On a ground from the body to the Frame, you could probably go with something more ridgid.