I was at the Denver Wood Working show late 07/early 08 and asked the rep. that was demonstrating the machine how he kept it so quite. You could stand right beside the CW and talk with out raising your voice. He pulled the muffler off and showed me the rag he had stuffed in it. Said it works great to cut down on the motor noise.
I tried it for a while and yes it did cut down on the noise but it also caused the motor to run hotter. I now run an 1 1/2 hose from the bag attachment to the shop vac intake. This cuts down the noise some but more than anything it helps with filtering the fine dust that is exhausted out of the motor.
This tip was posted by ChrisAlb and works great for me.
Do the reps still use the rag for demonstrations?