I'll ignore the shit thats just been spouted

Stage 1 - Usually one of two configurations. Either a std turbo bit with uprated seals and bearing, or std seal and bearing with a larger compressor - nearly always the former.

Stage 2 - 360 thrust bearing, staggered gap oil seal, and 55 trim compressor wheel with a std rear end.

Stage 3 - as above, but sometimes with a 60 trim wheel and always a 48 rear end