Snowpeak has come out with their own regulator for the Stormrider and Bandit. The full length version covers the gauge hole in the Stormrider pressure tube so you will lose your gauge in the stock and would be advised to buy the front gauge fill cap to replace that gauge. https://airgunarcheryfun.ca/diana-artemis-fill-valve-and-gauge-assembly/
For the Stormrider regulator you will need to tear into your gun and remove all the internals. The gauge block will be replaced by the regulator and so will the front half of your exhaust valve. You will unscrew the front of your valve and screw in the regulator, then slide the whole assembly back down the pressure tube.
For the Bandit choose the modified shorter version to save airspace in your pressure tube and increase shot count. This regulator does not require tearing apart the gun, as you can simply push it down the tube. Place the little air hole upwards when sliding it in.
The regulator is adjustable by turning the front flat head screw clockwise for less pressure and counter clockwise for more pressure. Before adjusting it make note of where it was originally so you don’t lose track of how much you have turned it.