You know that 20%HP increase for like what $9.99 that they sell on the magical E-bay  for the tracker motor?1.6?Anyone use this or know of someone?
Well, I put aside my embarrassment
long enough to try and save you the trouble. I bought one when they were $3.99 and almost no shipping cost. Easy price to charge because all I got was a piece of paper (instructions) and a single resistor. It wasn't a plug, module, or anything else; it was a resistor.
Now, that said, I didn't feel cheated. In fact, I had read before I bought it, that is what it was. You take the resistor and put it across the leads to the Idle Temperature Sensor (I think that's the sensor it was). That sensor will then report incorrectly that the air coming into the engine is about 20 degrees cooler than it actually is. It should then bump up the fuel mixture and change the timing with the effect being you get a little more power. I noticed an RPM increase at idle, but nothing more really.
I just saw a similar but much more advanced product on TrucksTV this weekend. It was a complete computer module plug-in harness (that went between the sensors and the computer) and would "massage" the signals coming from the sensors so that the computer would be fooled into providing more power. That had VERY effective results (like 2 seconds off 0-60 and 1/4 mile times!).
Anyway, for a few bucks it was an interesting experiment. For $10 or $15 for a single resistor, I'd say not to bother.