Yeppers. The u tube is upstream of the turbo. A hole will pull air in, like it does through the air cleaner but with a heckuva lot less flow restriction.

Worse, when I cleaned the inside if the u tube after buying the car it was coated with oil mixed with fine grits. It had been leaking a long time. Since I couldn't find a seal I kept it duct taped up. The seal was really deformed and not sealing.

I just got back from a drive and it runs great and makes good power. No worries.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles