[MrForbes]

If you put a restrictor fitting on the "vent" side of the piston, it will move more slowly with less force. You can also try adjusting the pressure regulator to use less than 60 psi, but the solenoid valve probably needs at least 20 psi to function properly.

I dont know if the restrictors are still included in the KOP, they used to be several years ago. The just have a screw fitting that you turn in to slow the flow of air.