Sorry, but there are a number of errors on that web site, or rather, things I do not believe to be true.
for a start, the engine did not up its capacity to 3.8L when going to 285bhp. the only 3.8s (as standard anyway) were the RSs, although the larger barrels can be brought as performance parts upgrades.
the information here:
http://www.idee.demon.nl/ is taken directly from the sales literature.
Also, here:
http://www.performance2and4.co.uk/993_1_n.htm refers to it as varioram, which from memory is written somewhere on the engine (probably induction).
Here are details of how it works:
http://www.instant-g.com/Products/36...sion/VRAM.html Hope that helps.