Different nozzle diameters in VNT 15 loaders?

Hello everyone,

The turbocharger needs to be replaced on our 1998 Passat with the AFN engine.
The current part is a VNT-15 from 1998 with VW part number: 028 145 702 H (listed in the AKTE HX catalog).
The replacement part is a VNT-15 turbocharger with Volkswagen part number: 028 145 702 C (as listed in the AKTE CX catalog).
In 1997, the CX was installed; then, from a certain production number onwards, the HX was used instead.

The older CX model has a significantly smaller diameter of the pipe stub on the pipe side.
With my limited understanding, "less cross-section" actually means less air.

Has anyone ever installed the old loader before, or can someone tell me something about it?

Thank you very much.
Stefan.