The ECU has control of the AMAL valve by pulsing the earth to the valve at varying frequencies. This is JUST for a boost curve and to drop the boost off it the ECU detects a problem. The ECU only drops the boost to what the actuator is set to lift at and the boost can be set to anything but the ECU will still control the boost curve.

On my car, the ECU controls my boost curve by the jetted AMAL valve. It is set to peak at 16 very breifly as it comes on boost and then holds 14 till the limiter. What ever I set the boost to, it will always peak and drop off 2psi quickly. If it detects a fault, the ECU will just keep the AMAL valve diverting air to the actuator as if the pipe went straight to the actuator from the compressor housing. This will limit my boost to 11 psi as this is what the actuator is set to lift at. If I dictonnect the AMAL or bypass it by the piping, it will only run 11 psi. The ECU and AMAL valve is what makes it peak at 16 and hold 14.