My 2ps worth - if you have the regular Sti2, rather than the RA (you'll know this by the adjustable centre diff and roof vent), you WILL have ABS iirc.

 

its an STi 2 V LTD, has a roof vent, not sure about adjustable diff though though, where's that located??

 

Its a roller-switch down by the hand brake, the movement of which corresponds to a series of lights between the revs and speedo on the dash. You will have noticed it I imagine, if you had it .

Anyway finding out if your car has abs is easy, Just find a quiet safe wet piece of tarmac, and do an emergency stop when it is safe to do. The abs should trigger under such circumstances, provided you are applying sufficient force to the pedal.