Originally Posted by 1slow370

grounding kits really only see their biggest (or any) gains on older efi cars. if you have a 91 civic si in your driveway go ahead and buy that grounding kit you saw in a super street, because it is basically a secondary ground system to replace your decades old and corroded factory grounds. on older cars they take a little bit of noise out of the sensor signals and improve spark that is where you get benefits from. if you have a good factory harness with clean connectors, and good signal it is a waste of 100-200 bucks