here's a quote from a site:

"The PFC F-CON is a pug-in fuel computer designed to supplement and refine the OE specified fuel curve. PFC F-CONs perform their function by modifying the factory specific injector pulse width based on information obtained from the OE ECU and the absolute pressure transducer included with the F-CON. This information is compiled by the F-CON and the resulting signal can allow for a longer pulse width for factory injectors or it can take advantage of larger injectors to ensure a proper air/fuel ratios during high air now conditions. HKS includes with each applicable F-CON a device known as the Fuel Cut Defencer (FCD). Several types of FCDs are made that raise the fuel cutoff point. This additional component allows the PFC to be effective at boost levels that would normally shut down the factory fuel system. The FCD, except in the case of Toyota's 1990 and newer 3SGTE engine, should not be used without an F-CON or some type of supplemental fuel system because the FCD will adversely alter fuel delivery without the addition of supplemental systems. The F-CON is installed by simply plugging in the supplied factory quality wiring harness, mounting and plugging in the pressure sensor, and plugging in the FCD where applicable. The installation of the F-CON provides the owner the opportunity to return the vehicle to stock conditions by simply removing the unit and harness. While the F-CON is preprogrammed with a ROM for each application, there is built-in adjustability accessible from within the F-CON to compensate for alterations to the HKS staged upgrades."

now I know. And if it has this.... what the hell ELSE did the guy add to necessitate it? I am WONDERING NOW! NOW I just need a tranny...

-Shawn