I posted this in the Stillen ECU thread but perhaps people can give insight or experience with the Super AFC which changes air/fuel ratio and thusly fools the ECU in terms of fuel curve adjustment.

I saw this mounted on the A'PEXi Z33 in a japanese tuner magazine. It should be a lot cheaper and not so invasive on the ECU.



A'PEXi website:
Modifies air-flow meter signal (pressure signal in some vehicles) to optimize fuel-air ratio. The second-generation S-AFC is a fuel computer that adjusts fuel/air ratio by modifying the air-flow meter/MAP sensor signal. The S-AFC features a user-definable, eight-point, adjustable fuel curve that can be set in 500 RPM increments. The range of fuel adjustment is +/- 50% at each of the user-defined setting points. The S-AFC is capable of monitoring and replaying the following data channels in Numerical, Analog Meter and Graph displays: Intake Manifold Vacuum/Boost Pressure, Air Flow Capacity, Intake Manifold Pressure, Karmann Frequency, Engine RPM, Throttle Position, and Air Flow Correction %.

 

my bad...i guess this was already posted.