It's a MAF (Mass Air Flow). Tell the bloke at halfrauds to concentate on 1.2 Corsas.
The dump valve issue is one that's been talked about so many times before, so do a quick search and you'll find out more than you need to know.
In short, the 1.8T engines use a 'recirculating valve', also known as a 'diverter valve' rather than an atmospheric 'dump valve', ie one that recirculates air back into the system; hence it's name. The recirculated air is read by your MAF sensor, and the amount read is sent to the car's ECU. The ECU then does it's clever bit of dictating the fuel/air mixture, etc. Basically, if you fit an atomspheric dump valve, the air is expelled into no-man's-land, and the MAF can't do it's job, so therefore the ECU can't, and your engine will not perform as intended by Audi.
Hope this helps.
Drew.
