FX Dreamline

My Dreamline 600mm barrel .25cal shooting around 910 fps is approximately 91db and around 82db with a Donny sumo
When I got the gun it was surprisingly not too loud. Equally surprising is the gun (Dreamline Classic) came without the hammer adjuster, something which is not made clear anywhere by FX. Anyways I bought the adjuster & installed it yesterday. From setting 1 to 5 the gun is at the same noise level as it was without the adjuster, anything over 5 & the bark is noticeably more. At setting 1 it flicks a JSB 8.4gr at 900fps, at setting 5 it goes up to 955fps. Anything over 5 doesn't bring any more velocity with the 8.4gr ammo, so l guess I'm not needing a moderator!