I have these fitted to my car. I understand the S-AFC can use a MAP sensor, as such does this mean my MAF is no longer being used?

The reason i'm asking is that if my MAF is used then I know I need a new one(engine doesn't cut when MAF unplugged), if not theres no point replacing it!

Thanks

Your MAF sensor is still being used...
...The SAFC is manipulating it's signal!

The SAFC is compatible with MAP based systems, not used on the Impreza though.

Richard

The Apexi SAFC is designed to be incorporated into the system which is fitted as standard as it modifies the output signal from the MAF so to increase/decrease fuelling.
Although the SAFC can be configured for various types of other sensors it has to be installed to work with the original system as the ECU in your case will still be MAF orientated but with a 'modified' signal from the SAFC.

Cheers