Patient is 2008 W211 E63, recently got heads removed, valve job done since it started smoking on cold. Head bolts replaced with updated version. 100k (km) on the odometer - the car is absolutely perfect, it idles smooth, no smoke, no check engine, revs like it should... except for the noise.

First thing that came to my head was bad radio installation - it literally sounds as if you had your amp cables lined along the aux cable - just whizzzzzzzzing with revs. But this would not be heard outside, would it? Also - it came up after the head job... So I started suspecting the PCV - and I was right, it was shot. But the noise is still there...

What else can be overlooked? Is it possible that tb seals make noise like this?

Sorry for bad quality, but it shows what I mean. From outside it feels like as if I had a compressor ;-)

(quick whizzz just after the wheel squeak)

 

Is your Y intake tube properly seated on the intake ?

 

I would expect it is properly seated... the car runs perfectly...
But something tells me I need to prepare myself to disassemble the intake and put it back together again with new seals...

Or is it going to be a waste of effort?

 

It would take to a proper shop and have it diagnosed and repaired professionally. So that you eliminate these issues in the future.