I have an A4 with the 1.8T 150 engine. Recently had it Revo'd. After a few hours of "energetic" driving I started to notice a hideous whine when any amount of acceleration was required above 2.2K revs; turbo spooling territory. Anyway, back to Drivers in Glasgow (they have been excellent) and a theory was formed of either a rupture pipe or the DV wasnt performing as it should. No fault codes were showing. So, I now have a Forge fitted and the problem persists. Im now looking at having to replace vacuum hoses. I didnt know there was more that one! Has anyone else experienced this or at least hear of other instances of spilt vacuum hoses causing whine under acceleration but completely silent while cruising? I'm hoping one of the Scottish lads has an idea tomorrow.