is the differance between the vafc and the safc is that the vafc is design for the vtec motor ?
and for my engine d15b jdm vtec the vafc will be better ?
and for the vafc i found jdm model and us model which is better to buy ?

VAFC is a vtec controller, along with air/fuel. SAFC is just a air/fuel controller. Either model, US/JDm will work.

thanks for adding info for me.

VAFC: VTEC Air Flow Converter
-you can adjust your fuel curve on a 50rpm incriment
-more control over A/F ratio which means better tune
-more $$, but worth it

SAFC: Single Air Flow Converter
-The SUPER AFC 2 is a fuel adjustment controller in which the pressure sensor signal can be modified in a 12 point RPM range by 1% increments to increase/decrease fuel in a range of +50% to -50%. The RPM to be corrected can be optionally set in 200 RPM increments
-Less money, but less accurate