The bottom bit ( with the biggest hole) goes onto the intake crossover pipe ( between the turbo and the throttle body). On top of the bov is a small nipple that you put a piece of piping on, and it connects to were either you've fitted a boost gauge, or onto the back of the intake ( here should be a pipe then you can t peice off).. and thats it.. usually you have to weld the BOV to the cross over pipe.

 

Thanks for the info Rexy, I just love learning new things I guess