Non of that make since to me. More power torque by running Stoich. I'll let more knowledgeable folks speak to it. If it came from e-bay it sounds like the .50 cent resistor that you can buy from radio shack that you put in the IAT sensor that fools it into thinking the temperature is either cold ( performance) or hot (fuel).
This mod has worked on a few makes of cars but not many. As SVO stated it will also increase emissions
I say scam.