I've seen that and like the Engine ground harmess (also on Ebay) I'm very skeptical.

The Performance chips for the ECU do much more than that thing on Ebay. The thing on Ebay fools the ECU into thinking the intake air is colder than it is so the ECU makes the engine run richer (adds more fuel).

The Performance chip advances timing and changes the fuel scheduling for starters. It also changes several different peramitters monitored by the ECU. If you have an automatic trans it also changes the shift points.

I will go with the Performace chip as soon as I see some hard numbers. All I've heard so far is some like.(not actual quotes).. "It seems to pull stronger" and "It sets you back in the seat more".