Whilst what Jano says is correct most of us a pretty clear what the commonly referred to stages for an RST T3 are after all these years...

Stage 1 usually thrust bearing upgrade only.
Stage 2 50 comp .36 turbine + thrust.
Stage 3 55 Comp .48 turbine + thrust.

Some offer cut back turbine blades and some also do a 60 trim comp wheel too (not recommended).

What he describes above would be a stage 3 from the likes of Turbo Technics, CR Turbo's, etc.