1999 Audi A4 1.8T Quattro - 70K miles

Replaced Turbo in Fall 2007

Catalytic ConvertorProfessionally welded 2 weeks ago

Noticing mild rattle noise at 3000 rpms

Changed spark plugs, back plug had fluid

Excessive Heat & Glowing Red Turbo / Exhaust Manifold base of Cat after normal driving

Could this be related to the newly welded cat? or Is the turbo going bad again.
If this is turbo, could there be something else causing the replacement of turbo. This vehicle has had two replaced turbos and has been adult driven.

Please post your opinion... Thank you...

 

aftermarket cats are complete garbage...