Defroster hoses

The nice thing is, the 2” hose fits on the heater box outlet snugly, and the 2.5” hose fits the slightly smaller outlet with enough interference that it would probably stay on by itself. A zip tie will secure it for sure.

You put the larger 2.5 hose on the smaller heater box outlet?
I want to order these, so tired of no defrost, but I think I am missing something here.
From the vent to the heater, this is my understanding of what you did, but it doesn't sound right. Can you clarify please?
2.5 to 2.25 - you ran 2.5" hose to reducer, to 2" hose, to the 2.25" heater outlet.
2.5 to 2 - you ran 2.5" hose to the 2" heater outlet.

Maybe I'm just too tired right now.