Will do. I've not had a proper look down there, but I have my suspicions about the vacuum lines beneath the inlet manifold. I think I can hear a hiss, but I have an untrained ear so it's probably me nitpicking.
What conviced me to do the mod was a thread on some Audi forum, where someone proved that the n249 was creating an erratic boost curve, especially when pushing the car on the track. Hopefully it will let the boost build quickly and smoothly, and not interfere too much when having a spirited drive. It seems more of a safety feature (maybe to do with the recall of the mk1 for those 5 or so deaths) for the driver rather than the engine itself.