The VAFC is made for use by the Honda/Acura crowd. Not only does it have a VTEC controller built in, but it comes preconfigured for use with a Honda speed-density fuel injection system.

The SAFC is the same thing without a VTEC controller that can be used on pretty much any fuel injected car and is reconfigurable to different FI systems. I would use an SAFC on my car to be compatible with my MAF type fuel injecion system.

If you have time to dyno tune the thing, gains of 5-10 horsepower wouldn't suprise me.