Rattle/Grinding sound while RPMs come down

[C2102]

Hi all,

Picked up a MK7 ST at an auction recently and there’s a rattling/grinding sound issue.

Can replicate the sound while standing, revving over 2k RPM and then letting off. Seems worse while driving and while engines hot.

Occurs after getting up over 2k revs and then on the way down there’s a rattling/grinding type sound from the driver front side.

Thinking it could be the turbo actuator?

Also have this strange red pipe up front, been told it probably had a dump valve on before. Could anyone confirm what it is?

Thanks in advance