People can inflate their eBay ratings. It's very easy to create more than one account.

What this guy is selling is probably a simple resistor that can be purchased at Radio Shack for 37 cents. It hooks into the IAT sensor and alters the reading it gives the ECU to lower IAT reading which forces the ECU to give the car more fuel making it run rich. Bad idea, really wear your engine down. And it's a huge scam, you can do the same thing for about a dollar if you take an adventure to radio shack. Plus I doubt that it really adds nearly as much performance as he claims.

The grounding kits actually do do something, but not very much. The more modified your car is the more effective the grounding kits are. If you have a large amount of stereo equipement or electronics in your car it will also help increase performance by grounding out negative noise from those devices. The ground kits provide a more sustained voltage to give the ECU better performance. You probably won't notice it, though. They're more for looks inside the engine bay.