It is a known problem for sure. This guy has a fix.

http://www.thesamba.com/vw/classifieds/detail.php?id=840864

Mark

Tom Lambas wrote:
> I just put my first piston in (not german) an found the deck height to be
> 1mm low. This is a 2.1 with the original crank&  reman rods.
> If I go ahead with using these pistons am I likely to have any problems? I
> know power will be reduced with the lowered compression, anything else?
> Has anyone here tried it? The manufacturer has kindly offered a refund or
> exchange but says many people use them with no problems - seller says the
> same.
>
> Thanks, Tom
>