A turbocharger is constituted by 2 wheels on a common shaft, a compressor wheel and a turbo (aka expander) wheel.
The compressor wheel is the "cold" wheel - it operates in the aluminum cover on the ds of the car.
The turbo wheel is the "hot" wheel - it operates in the cast iron cover on the ps of the car.
The stock turbo, a Garrett TBO348, has a nominal 3" inlet (compressor inlet) and a nominal 2" outlet (turbo outlet).
strike