got my a3 a couple of weeks ago and thought it was ok, got it mapped a few days ago and the guy that done it said it should be alot quicker, i didnt know because i had never drove one before so now im trying to source my problem but not sure what is a commen problem with these engines, the exhaust is blowing up about the manifold but i cant see exactly where, would this cause it to lose alot of power? people have mentioned n75 boost controll valve? and also air flow meter, i unplugged the air flow meter and the car drove the exact same so does that mean its broken? its so annoying not knowing what to do