rclamb

Dealer just told me I have a bad bearing in my K03, suggested replacement. It does make loud noise under heavy power. Can I get any performance gains with just adding a new k04 without any other mods?

Electron Man

Yes, the K04 will give about ~15 more HP (even on a stock chip).

You should probably get a GIAC or other chip later though to realize full potential of the K04.

xr4tic

I remember reading how some chips for the K03 can be run with a K04 with no problem, but others could not (or wasn't avisable)

You should be fine just swapping turbos, the K04 will run more efficiently at higher boost levels, so it will make more power.
If you got a chip for it, you will also need to put more fuel in, so you'll need to get injectors or a 5 bar pressure regulator. But I'm sure you'll like the results

rclamb

Thanks for the good replies, it really will help me out in my decision.