I'll be interested to see how your engine idle with climate control on, copes with the decreased load on the engine.
Last time I fitted one, it was to a car with air-con (not full climate) and the idle is way out...it's about 300RPM high as the ECU adjusts the idle when air con cuts in / is switched on, but the engine no longer has the same load on it...hence the high idle.
Oh, and it fails it's MOT because of it!
I would think the S3's ECU would be able to regulate idle more effectively...but time will tell.
Please let us know.
As ScoTTy says, it will be rougher at idle, and stall more easily...but it should rev up a bit smoother....but I'd not expect lightening fast revs as the cams just don't work that way on a 1.8T.
An interesting project though.. /ubbthreads/images/graemlins/beerchug.gif