A quality suppressor will eliminate 95%+ of the muzzle blast. Remember that decibel readings (increase or decrease) is logarithmic (think pH scale).
If I shoot subsonic 22lr ammo (e.g. Wolf) through my Sparrow, it is Hollywood quiet. If I shoot supersonic (e.g. stringers) through the Sparrow, it is no where near as quiet due to the sonic crack. Remember that and you will not be disappointed when using a suppressor on any caliber.
