also boost psi isn't everything. Volume is another measurement that is required when considering
The stock turbo can produce high boost, but the volume of air is not going to be there for applications much over 200HP. You would have to step up to a larger turbo such as a K04 or a GT28RS. I pull about 17 psi with my high flow cat, Borla exhaust, and APR chip and factory k03 turbo. It's about as fast as my old 93 TSI AWD that I had. And I had a test pipe and and modified boost control solenoid. I've had less major problems with my Audi than I had with my TSI AWD. But the audi requires constant minor work. And that is what kills you. I have 156K miles on my A4 now. Things like control arms, timing belts, tie rods, wheel bearings, the list goes on. But I have not had any engine problems, transmission problems, ect.
My TSI AWD had 3 transmissions, 2 rear diffs, 2 or 3 xfer cases, valve lifters, was burning oil at 120K miles over the 5 1/2 years I owned it.