That is the sound of our quality 660 freehub mechanism. Six degrees / 60 points of engagement. It also serves to scare off prowling cougars. This is useful in town and in the hills.
If this loudness really bothers you, we recommend pedaling or going so fast downhill all you can hear is the wind.
Alternatively, a healthly application of Redline Gear Oil will knock a couple dB out of your hub and keep your freehub ratchet working great.