Suppressed SMGs aren't totally silent, but they're pretty silent. I found a few good videos on YouTube. I remember how in the SR3 BBB on the perception test tables it for example gives seperate TNs for detecting a silenced gunshot, as opposed to treating it as being totally silent. I guess that a component of any quality RPG or video game should really be degrees of silence for suppressed weapons.
http://www.youtube.com/watch?v=3UclVL1COUQ...feature=related
http://www.youtube.com/watch?v=vTlhq1cFdiA...feature=related
I ought to retire in a state that would let me own automatic weapons like that...it would be a great retirement activity to operate them.