I've observed that when you kill the first group of enemies you meet in Chapter 5, with the default silenced pistol and without any enemy being able to fire a shot, enemies won't be alerted to your location and Max Payne will comment on the stealth kill. (I'm not sure if not doing a stealth kill will change how this part plays out, though [like enemies being alerted and immediately attacking at that part if a non-silenced weapon was fired]).
However, it seems that this doesn't seem to be the case with the next group and the rest of the enemies you will encounter in that chapter. It doesn't seem to matter if it is a stealth kill with a silenced weapon or if you use non-silenced weapons - all the enemies in the level will seem to be alerted to your presence if you engage in a gunfight with any enemy. This leads me to believe that the 'silencer' of a weapon does not really matter that much in most parts of the game.
Hence, my question: Which parts of the game's Story mode, will successfully doing a 'stealth kill' with a silenced weapon affect gameplay? (i.e. Max Payne commenting on the stealth kill, enemies not being alerted to your location or other gameplay changes)