chip and catback exaust can boost the 1.8t to around 230hp.
Best bet is do alittle research in the Performance Forum. Check out the I am looking to up the HP in my A4 thread.
the stock T03 turbo with a stock ECU runs 7psi
Here are some stats(give or take for other mods...):
Stock K03= 146hp
K03 Chip = 172hp
K04+ecu = 220hp
why dont you want to change the turbo?