[Richard L]

Both HFS-3 and HFS-6 uses the fuel injector signal as prime source for flow control. Th HFS-6 has more F-IDC re-scaling function compared to the HFS-3's idc gain only.

For example, if the incoming iDC is 30%, the HFS-3 can multiply x2, 1 (default) or divide it by 2

The HFS-6 can pre-offset the same 30% signal by +/- 20% before the multiplier. It will also compensate the idc due to increase manifold pressure.

Gauge and failsafe is identical except the HFS-6 trimmer the failsafe reset timer compared to the HFS-3's 3 seconds.

Flow control valve is the same on both except the driver circuitry is built into the FCM.

Both systems can reduce boost to wastegate pressure of cutting the control line of the boost controller to the BCV in the event of failsafe activation.