Air Leak
 

Having a bit of a problem.

Just came back from G/f house, and I have noticed a hissing sound from the engine bay, I'm guessing by the BOV Valve area, it starts when it starts to boost, and although the turbo is blowing, it seems as if the pressure , or most of it is being released. My first guess is a faulty Blitz BOV Valve, but before I shell out money for a new one, does anyone else have any ideas??

Check the gaskets and connections on your IC piping and exhaust and make sure that the BOV and any other adjustable turbo stuff is set correctly. Check the connections for your boost guage too, faulty guages have cost me engines before.