NOTE: This mod only takes a few minutes.
Step 1: First, Some Numbers
-Ambient Noise 48 dB
-Ninja Mouse 52 dB
-Regular Mouse 74 dB
(The regular mouse is just as loud as my Ninja Mouse used to be.)
If you know about logarithmic scales, you can see Ninja mouse is over 10 times quieter than the regular mouse!
Step 2: Open It Up
When you get inside, locate the mouse switches. You should see some rectangular boxes like in picture 3. If you have the square switches like in picture 4, you're out of luck. There isn't a way to quiet them down that I found. (They use a thin, metal concave disk than flips to being convex when pressed. Putting anything in there to quiet it down makes it lose all functionality.)
Step 3: Open Up the Switches
Do this in an area where with dark flooring. That little white button likes to get away and it's really hard to find on a white floor.
Step 4: Press Down the Tab
If you bend the tab down too far, just bend it back with the knife. The metal is quite malleable.