Air leak/ noise from airbox/turbo area

After some help/advice guys.

1.6 Diesel Turbo rapid saloon.

I have a loud "air leak" noise from the inlet/air box side of the engine. Only started happening last night. Only happens in gear when under load and the turbo is boosting. Cannot create when stationary or in neutral. Sounds very much like I have a dump valve fitted (which I don't) I have not had any loss of power or performance, and I have not had the "dieselgate" recall fix on the engine. I have had no fault lights come up, and my daily commute is 120 miles so no issues in that distance so far.

My assumption is a pipe/hose has split or popped off, but I cannot see anything missing/loose/ broken or split.

Has anyone had this before or know of a "usual" suspect pipe, and is it bad for the engine. 

I know someone who is running a similar engined golf with a cone filter which makes the same sound which again makes me sure it is an inlet side of the air system as it is sucking in more air. He is a bit pi55ed off that I have got the noise for free and he had to pay for the filter set up LOL!!!

Any info would be of use,

Ta