I drive a 2004 sti, and it is possible to get the back end out at exits if you set the differential to 65% rear power bias. 22b came with a DCCD (driver controlled center differential) to be able to set this manually. you dont need handbrake to drift it, just play with the steering (not counter-steering) and throttle.
low and mid speed sections are easy to get the tail out, you need to steer hard and throttle hard at the same time so that the front pulls initially causing the car to rotate more.
in high speed corner, stock sti's will have mid corner and exit understeer because 1)not enough power at that speed to coax it 2)stock suspension is setup up this way.
I drove the 2004 sti with my real life settings (Track Dailed suspension with slight power-oversteer on exit)....offline was just hopeless cause even with the upgraded diff, its still pushing at exits. but online was so much better as I can rotate the car or get the tail out slightly at exits.