I assume you are speaking of a grounding kit. That would in turn ground the throttle body.
Gounding kits provide a more consistent ground to all components. They have consistently shown HP gains of 2-3hp on most cars. The problem with such a small gain is that you can never really be sure if it was the Grounding Kit or just some dynamic difference in the environment. The real gain that grounding kits claim is better throttle response and better/faster shifts in AT cars. I personally think that there is truth to the better throttle response. On every car I have had one on I have noticed better response. Now spending 150-300 bucks on a grounding kit is rediculous. You can build one for about 25-50 if you are willing to take the time.
