Dpf and egr delete/remap causing turbo issues? about to need 3rd turbo in 2 months TRANSPORTER T28 TDI HIGHLINE

Had a dpf delete, which I don't think is the issue but following the removal of the exhaust filter a couple of months ago, the turbo started screeching and was replaced.

About 100-200 miles down the line the day before a long time planned trip the turbo blew accelerating to 70mph, black smoke everywhere.

Turbo was then replaced, and the van is back to normal for about 200 miles where it blew again in almost the exact same location while driving at 60-70 miles an hour.

Everything in the van feels fine, nice actually. I'd only add that it felt like the two new turbos were lacking power slightly compared to the original. I'm stuck now as the mechanic is unsure and probably have to do a crazy deep dive into the issue, and the guy who did the tune doesn't think it's anything to do with the tune and believes it's something oil based. I do trust both guys, they're both knowledgeable and professional.

Wondering if anyone has any ideas, similar experiences? Any help at all would be greatly appreciated
 
Was the tune done before the DPF?
Was the DPF itself worked on (cleared out) or just a software delete?
If the DPF wasn't cleared out I'd say that's the issue otherwise I'd drop the tune to rule that out.
 
When they removed the dpf was the cat part inside the dpf left in or was the whole dpf removed.
 
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