The newer driver is not a peak and hold one, so it will not keep the injectors open for the entire pulsewidth, especially at idle. The versafueler is more advanced than the box of resistors in the AFM driver. I'm having a good bit of trouble getting the car to idle. There were a few guys on the turbo forum that switched the the versafueler and saw notable improvements in idling and drivability. It may make tuning the car easier in general as well. The nice thing about the AFM driver is that it just plugs in. I need to splice in the other one to the injector harness.