Ive not had a pcp that hasn’t benefitted from having a reg fitted, its not necessary but the improvements can be big. It depends on what you want or like, some rifles deliver a small gain in one area while others are transformed.

Ive always regged my s400’s were some say no need, my s400’s shot same fps from shot one through to last shot on reg whatever the fill pressure , higher shot counts, easier cocking, less rapport. My Benjamin Akela went from 65 shots in a 20fps window to 325, Kral npo3 from 40 to 75.

It depends on what you want and how you fit reg, just fitting it will help but balancing the parts is the key, not done the rifle in question but have yet to see a worse rifle after fitting a reg