Well, I own a VSC phantom w/45, and I have putten a silencer on it, and all you hear now is the ball moving through the air. You cannot hear a thing, but then again, it's not shooting out 15 balls per second.
Well the only part of when I shoot my B2k is when you hear the bolt hit the ball...Other than that I hear a little bit of other noise but I would say a nice trix is the quietest.