There are two sides to a turbo, Compressor and Turbine, they are connected together through a shaft that goes through the center section. Turbine side uses the exhaust to spin the Compressor. The compressor side is the one that pushes the air through the intercooler, and into the engine, the compressor also pulls in air from the outside, that's where you'd hook up your Cold air Induction or pop charge filter, or whatever else you can think of. If you can find a picture of a turbo somewhere, there's bound to be them all over the internet you'll see what I mean by two sides.