You dont need to tune for the intake in most cases, unless the diameter around the MAF is bigger/smaller than stock because then the MAF will read wrong and your engine will run like ass. An intake probably wont do much in your situation, other than make things louder and give suction noises but an intercooler might. You'd really be pushing the turbo if you want more than 260hp. Considering how weak the k03 is as far as reliability, I wouldn't push it any further since a properly tuned k03 will spin till the end of 2nd gear anyway. It's small and cant build boost past midrange like a k04 can, it's just not worth to overstress it. K03 accelerates hard, and I mean HARD from 2.2k onwards but lacks the top end oomph of the K04.
If you want more power, I'd swap to a k04. Been there, done that cause my k03 failed. Hot side cracked right around the wastegate and the turbo shaft had so much play, only the will of god was stopping it from coming out.
If you want to stay K03, you best bet is an aftermarket intercooler. It will keep temps lower and flow better than stock, maybe freeing up a bit of power.
