I had one fail instantly.
81 Scirocco, 1st gear full throttle start, approaching 4-5k rpm, hit a big
pot hole with pass side tire.  The outer cv on the pass side blew up.  The
cage broke into multiple pieces and the car coasted to a stop, no matter
what gear I was in.  I thought the diff broke, and was really scared to
think what my girlfriend was gonna do to me.(her car).

The was the only VW cv I have ever seen fail without warning, at least in a
stock hp car.  My friends G60 rabbit broke all six bolts that held the inner
cv to the drive flange.  And another buddies turbo scirocco broke an outer
cage on the 1-2 shift.

Sorry for no van content, but the Vanagon cv's are very similar.  Hopefully
200hp wont break those.

>  Can any of
> you verify this with your experiences?
>
> In my experience, VW CV's give lots and lots of warning when they
> are about
> to fail.  I have never had one fail as I always replace them
>