On a MY98 Impreza Turbo, coming from the bottom of the large flexible pipe that goes from the air box to the throttle (i.e the bit where an induction kit would sit on the end of) there is a little pipe coming out which connects to another small pipe. This comes from the black cylinder (coke can sized) thats behind the drivers side headlight. Just curious as to what that can be putting into the intake? Is it merely some kind of breather pipe?

 

The black cylinder sounds like the carbon cannister, so it'll be to do with the emissions system.