Fiocchi 40SWD: Pistol Shooting Dynamics 40 S&W FMJ Flat Nose 180gr, 50/Box
This is stupid quiet through a suppressor. Sounds like a heavy staple gun from an HK P30. Not too dirty. Completely awesome if you're shooting suppressed. Pointless if you're not shooting suppressed, though. Subsonic 9mm does not have great impact, and this is FMJ anyway.