Well with the new content drop from Call of Duty ELITE, a new Title Update has been given to the xBox. It changes the match making system by whatever region the party leader is in. It also gives support for the two new Spec Ops missions, Kill Switch and Iron Clad; as well as two exclusive Face Off maps, Getaway and Lookout; and a multiplayer map called Oasis. It also increased the prestige limit to a whopping 20 prestiges. It also fixed a Rapid Fire glitch (I have no idea what the glitch was). It also modified the pro effect of SitRep.
In the past, Dead Silence muted your footsteps (supposed to be 75% but you still can't hear the player). The pro effect from SitRep allows you to hear enemy players footsteps 4x louder. Before this title update, players with Dead Silence could never be heard, even with SitRep pro's 4x sound boost. After the update, a couple of characteristics of SitRep changed - the player can now hear their teammates' footsteps and the pro version now counters Dead Silence.
- http://community.callofduty.com/message/106065898 - Official Patch Notes for MW3
- Youtube - TmarTn MW3 Tips and Tricks (SitRep vs Dead Silence after patch)