For the Artemis (Spa / SMK)  P15/P35 we have a tuning pressure regulator available that replaces the original chinese regulator.
This is an one-on-one replacement, just unscrew the old regulator and screw the tuning regulator and you are ready.
This regulator is vented to the atmosphere without any modification to your pressure tube. So no drilling in the tube and also no creeping up in power during time