[Biturbos4] Can someone explain the Snub mount to me?

[MattOVR6 at aol.com]

I am curious as to what the popular "snub mount" is, what it does, and how hard it is to install..   I am assuming that it fits somewhere up by the radiator support, and prevents the engine from excessive movement.  

When I shift, I can feel the engine moving, and feel a small clunk when it does.  It's a very faint clunk, but enough to bug me.  Would the snub mount fix this?

For $25, you can't really go wrong, but is it going to be $200 to put it in?

Thx for the help!
Matt O.
o-bars.com
00' Nogaro S4