Audi A4 2003 1.8T Automatic Sluggish Underboost

Good afternoon to all.
Audi A4 1.8 Turbo petrol Automatic 2003 United Kingdom right hand drive.
VIN: WAUZZZ8E94A133015
Engine: BEX

Fault code is P0299 - Turbo/supercharger under boost.

The issue is it very sluggish got no go in it. Put it like this. If you was to pull out of a junction it be suicide.
A friend of mine noticed this pipe what comes from the turbo but is blanked off by a bolt and he cannot work out where the other end goes.










Thanks in advance.
Regards.
James