I have a 2000 audi a6 tip that is stage 3 and I have a 3 inch downpipe with high flow cats. The problem is that because of the size of the downpipes, they rub right up against the frame of the car and the transmission pan which does cause some rattling, more commonly at idle. I wanted to get an opinion from others what is an appropriate size for downpipes with stage 3 and have K04 turbos. I have been thinking about getting smaller high flow downpipes like milltek or others so get rid of this rattling and some of the drone. Are there any benefits to gain with 3 inch downpipes or would higher flow 2.25 or a 2.5 inch downpipe be fine for a stage 3 setup. Again I am a tip tranny so I am not going for high horsepower numbers. Does anyone know the diameter of the milltek downpipes for these cars. I have a magnaflow 2.5 inch catback exhaust.