[DiGiam]

I Dont know what the surging is in this case but i can only tell you what my experience was with my first ported throttle body. I had one of the first ported throttle bodies for the 6th gen and it was opened up good with the throttle blade shaft cut down like this one. I experienced the surge you are all talking about. I was able to data log it and saw what it was doing in HP tuner. The best way i can describe it is the computer is seeing way more airflow than it can compensate for so it is sitting there opening and closing the throttle body and causing that the surging you're feeling. There is a fine line on how much can be taken away/ported before the computer acts up and it requires a tune. In my case I just went back to the stock TB and it immediately went away. anything over about 28% throttle input was fine but under that it would surge with the ported one. I later ported my own following what id learned listening to others and the surging went away but the throttle response wasnt as good either. I sold my car back in january because the A8 is an enormous piece of shit but im sure this surge could have been fixed in the tune but i never dug into it that far.