That's not easy to guess, I'd love a couple of extra angles to be sure.
The charge air hose to the right in that pic looks like it could be slightly split facing the EGR tube on the left of the pic. If you don't have a catch can, you'll have a small amount of blackish oil entering the air intake from the PCV (top of the engine at the rear and connected to the air intake just in front of the turbocharger intake). This could be emitted anywhere along the intake path where you have a leak.
If that's the case, you may also be hearing a shrieking sound under boost and may be experiencing a loss of power to some extent (whether you can tell, or only measure that loss, depends on how bad the leak is).