Hey AJJ, At the top of your engine, nearest the windscreen, on the back of the black part, labelled "Turbo Intercooled", there's a little tube that acts as a natural sort of blow off. If u take it off the nipple, you start to get the blow off sound, which is the turbine cutting up the excess air which isnt being recycled by that piping. Ive been told by several mechanics that there is no damage to the turbine, and if u want to get rid of the sound, the hose needs to be securely on the nipple. I found out about this when I got my car back from service. Sometimes they forget to reattach the little vacuum hose. Personally I quite like the sound, gives it a little bit of oomph when your driving. Ive been driving for a couple of weeks with the hose off, and whenever people hear it, they smile and comment on it. ----------------------------------------------------------------------------------------------------- Is this the one that goes into the Rocker Cover ? The little breather looking device with a tube that runs down to the intake manifold ? Pete