I applied a silencing mod to my HHKB Pro 2 a la
http://geekhack.org/index.php?topic=40582.0. Using the following:
I punched a hole in the rubber sheet then cut out a box and trimmed a ring so it would fit the plunger.
This worked surprisingly well even though the rubber sheet I bought was super thin (was harder to deal with because of how thin it was). It successfully silenced the cheap feeling/noise when the keys come back up after a key press.
I believe the key feel is exactly the same but I get more of that "thock" sound almost completely eliminating any high pitch clacks from the keyboard. I like it a lot more now

Unfortunately the only photo I took while doing the entire thing is super blurry and taking the keyboard apart takes far too much work. If anyone really wants to see any pictures or videos I can take them.