Are you trying to get the thing QUIET?! Like, no noise but the cycling of the action? I can come up with something that's under 1,100fps for you to try out. Shooting supersonic ammo through the suppressor will still give you a "crack," but it'll take alot out of it, overall.
Hunting with this thing? Texas piglets? Please tell me this is for "quiet wild hog eradication in the neighborhood..." <lmao>