Are you people nuts? I don't see how you think this won't be OP, you arn't considering the full range of possibilites.
EXAMPLES FOR SILENCED HUGE: (Assuming the player had aimed down the sights)
1. Kill someone standing in a corner without players knowing what weapon was used and players far away would not hear it.
2. Kill 1 or 2 players down a hallway, anyone who doesn't see the person leave the crime scene won't know what weapon was used to kill them. If another Traitor used the flaregun then it would be even worse, as the Innocents don't know anythin exept a weapon was fired.
I say that that is pretty OP. Now if a Deagle was silenced, a Mac10, a sniper, or [the other SMG] it would have much the same effect. I say that it would be a bad idea to add an equippable silencer to certain weapons, specificaly SMGs, Rifles, and Assualt Rifles. The current silenced pistol is just fine. If you dissagree I want a counter-argument.