A3 3.2 air leak?

[Whodafunk]

I have a 2007 A3 3.2 Quattro. Today with the hood up and engine running I have noticed what sounds like a small air leak when I blip the throttle. Almost sounds like something blowing through a tube if that makes sense. It's got that sort of sound to it.

I have a fault code for rich running on bank 1 cylinder 1 which I've had for a while. Could be down to an air leak I'm thinking. Car runs fine though and no other faults. Any places to check for leaks? I've had a look around the intake manifold, vac/breather hoses and everything looks good.

Sounds similar to this noise but not as loud...