Ratchetty type noise....Help

[bobster]

I can hear a clicking noise coming from the general area of the turbo pack/intake hoses. It\'s kind of like a ratcheting noise. It isn\'t there when the throttle is open any amount. It only appears when I come off the throttle and the car is slowing down. Dont hear it when the car is sitting idling.

Does anyone know what it could be?

I am guessing that it is in some way related to my boost problems. i.e no secondary