250whp on stock turbo?? youre nuts. not through a quattro system. and that power mike savko made on that car in the thread he made was only for a few hundred RPM. the k03 simply cannot keep up with the demands at that point.
i do agree 28RS or bigger… a 2871R, with a .64 housing a great turbo for a 250-280whp stock bottom end setup, on conservative boost or even a T3s60. great spool in a 1.8t and since its an AEB head it will flow better. but making upwards of 300lb/ft of torque on stock rods has proven to be hit or miss with catastrophic failure. building an intercooler setup for an A4 is pretty easy too, so a Precision 350-475 core would be great for using with custom piping.