Quick 04 question

[SS Laser]

My Dad's work truck a 04 f550 has had the egr replaced then the intake because it was "plugged". After the intake he noticed it ran really rich and had a howl. So back to the dealer. The mechanic found a quarter size hole in the turbo outlet rubber pipe. So they replaced it. The mechanic reved the truck, bang another whole or split in the brand new rubber pipe. They called ford, said keep the truck will ship out a turbo.

Why did a faulty turbo cause this? My dad said it runs like it use to now with the new turbo.

I have been messing with gas turbo engines for over 10 years. But no diesel stuff. We wonder what happened. Did the VGT get stuck wide open? Does that help the turbo regulate boost? If the VGT was wide open did it make a bunch more boost. I thought boost was regulated by exhaust housing size and rpm?

Please help educate me!

Thanks for any help,
Wayne