Since I have gone stage 2, I have noticed a marginal amount of DV flutter under full load.
One option was to back the boost off using the Revo Select switch, but that would be sensible and cheap. Instead I have decided to throw a few quid at the revised OE VAG diverter valve:
New revised DV (link - see bottom of page)
Older style DV (not my DV - web pics)
Ordered from JKM last night for about Ł50 inc postage. It looks OE, will raise no eyebrows when serviced, and should hopefully have better performance than the earlier revision version.
Will feedback with any observations once it's been fitted.