The grounding kit is a simple way to ensure smooth signal response from all the fly by wire components in the 370Z. Many people can attest to the gremlins you can face chasing down a poor ground connection. Having the Stillen kit is a way to massively increase the ground path between components and therefore achieve the fastest possible signal response between components.
Placebo effect? Doubtful. HP gains? Doubtful. Insurance against signal dropoff and degraded performance over time? Guaranteed!
I bought mine with other parts from Stillen and as a Military Electronics/Optronics Technician, I can definitely see the benefit to having a grounding kit versus not having one. Well worth the minimal cost of these systems.
