I think your confused a little.
Japan:
Spec R - SR20DET
Spec S - SR20DE
Australia:
Spec S - SR20DET
Spec R - SR20DET + rear spoiler + side skirts + sunroof + 6 cd stacker
So in Japan, Spec R is the turbo version while Spec S is the NA.
In Australia, both Spec S and R are turbo.