I just removed the grounding kit two days ago because my car has sold and will be leaving in a week (which was only consisted of two wires going from the neg batt terminal to: the frame and the engine) and ever since the car has been running very terribly. By that I mean totally bogging to the point that it has almost killed it. I cleaned the maf sensor according to the guide on this site, still no fix. I ran it many times in the last two days to try to allow the ecu to adjust, but still nothing. So I put the kit back in and now it runs perfect.
So basically for any grounding kit users, your car will now be too addicted to the grounding that it wont run without so don't expect to be removing the kit.
Btw, anyone tell me if they've done the same and Not had it happen.