I just bought a 2000 A4 quattro and I'm not really sure what the stock boost is. I do know that stock HP is 150 and 200 is available with just a chip (i.e. more boost). The turbo is very very small though and you'll go beyond it's capabilities very quickly. I've talked to a few companies that claim they have around 230 hp (crank) on the stock turbo without NO2 or anything very extreme.