Benjamin puppy power plenum

I have a .357 Benjamin Bulldog bored to .3125, pitbull power spring, polished barrel, barrel supports. I’m going for maximum power, accuracy obviously counts but I think that shouldn’t be an issue. I’m looking at the extended reservoir for the next power upgrade. But I see the puppy power plenum 160cc would get you to the same spot. What’s the difference? I know he says 3k but he can’t recommend above. I’m personally wanting to run 4-4500 if possible but I guess we’ll see when we get there. Anything other you can think of to get it slinging as hard as possible let me know. Thanks!