Originally Posted by Josh@STILLEN

Grounding kits are effective in a number of ways, and have huge performance improvement potential on older vehicles, as years of crap buildup and things with connections and the like. Obviously with newer vehicles like the 370Z's, less performance gains are there, but it will set you up for less drop off of performance due to electrical ground issues as the car gets older.

Some feel bigger responses than others, but it's especially beneficial for those with automatic transmissions, and you'll read all over the place of people reporting snappier shifting and better shift response times with the grounding kit installed.