After a bit of research, that "pipe" is part of the EVAP system which prevents hydrocarbon emissions from entering the atmosphere by storing fuel vapors and routing the vapors to the engine to be consumed during normal engine operation. I did not find any info that it was also used for crankcase ventilation as suggested by post #6 but it's not out of the question.
Pertinent to the ST:
- On turbocharged engines, an EVAP ejector is used to create a vacuum in the purge line during boost conditions. When in boost conditions a percentage of the boost pressure is applied to the EVAP ejector to create a vacuum. This vacuum draws purge vapors through the EVAP ejector into the intake air system upstream of the turbocharger.
So, this is part of the EVAP system so it will function under boost conditions when there isn't vacuum to route directly to the intake manifold.
Don't play with it.