Question My SCF Pedal makes a loud "pop" when being engaged and disengaged. How can I solve that problem

I guess you are using external A/B switch box in which the outputs of the SCF are disconnected when the pedal is disengaged In that situation the DC offset on the SCF outputs will tend to grow slowly (due to a minor DC-leak in the output capacitors) and as you engage the SCF you will get a pop. This artifact can easily be removed by mounting a 1 Mohm resistor across the output jacks. Please refer to the attached drawing.