for k03s you need to either mod your turbo inlet pipe.. get it machined out by a few mm (i have my old one already modded if you want to make an offer

) or use a silicone one like i did eventually.. 4 bar FPR and a suitable remap. exhaust/cat/dpipe really help a lot too.
not really an earth-shattering difference.. i only did it because my k03 died and i got a really good deal on a brand new k03s.
im sure this info is already on here in great detail if you use the search
