As they have all said, yes it does. Replacing this part gives you a little more power, but not nearly as much as the pipe itself. The most benefit you will recieve by replacement is weight loss on the bike. The stock exhaust parts are as heavy as boat anchors.
Another thing, if you plan on riding in ORV parks or in Hare Scrambles, Poker Runs, or any other organized event that doesnt take place on a MX track, it would be wise to replace the silencer with another S/A. Most places wont let you ride W/O one.
B.