That's good to see, and well done for actually testing it. I fitted one to my old TT6 Supra and it did feel a bit smoother.
I never done anything as in depth as putting a scope on it, but I did measure the resistance from battery ground to different areas of the car before and after. On average I saw a 0.15 Ohm drop in resistance with the kit fitted. So I figured it must do something.
Maybe I'll get round to fitting one to the zed, I've had one sitting in the garage since I bought the car.