SAFC as he sed, fiddles with the airflow signal so the ecu give more or less fuel. Only down side is SAFC can not tune ignition, so its only can do so much. That sed it can be useful for R33's, gettin rid of that nasty Rich and retard it does wen the ecu senses too much flow.
Looks at lilhaulerz post.
http://www.skylinesaustralia.com/forums/Wo...fc-t232836.html
Gained a good 30rwkw from the SAFC tune, and lots all over the rev range. A worth while and cheap mod for those that dont have the coin to go full ecu and have just basic bolt on's and mild boost. 190-200rwkw for street is still quite fun. Anymore than this than get ready to open that bank cheque. !!!