When driving at fairly high speed with my foot only a touch on the throttle there is a loud hissy air noise from the engine bay, if i press down a little more the noise goes, back off the gas a touch and it comes back, hissing constantly until I change my throttle position, what is this out of curiousity?

 

TURBO

Only happens after application of right foot above 3000 RPM?

 

definately not the turbo, boost gauge shows turbo is out, seems like a sucking air noise, no induction kit, YET!!!! so still no idea.

 

Its the little man in you head saying,

"sssshhhhh, give it some welly"