Hi my name is Joseph I am very new on here as well.
However I have a red Audi 2000 A6 2.7T Twin I am working on getting my ECU flash by a someone on this forum. What he is going to do for me is flash my ECU to a stage 2 for $ 450 which is very cheap. My turbos will be at 20-21psi on the stock Ko3's. For you I would do the ECU first then get yourself a intercooler, then worry about the down pipe. If you would like I can pass on your is info to you if you like.