Tunnel ram or no tunnel ram...

My head is spinning! I don’t want to highjack this thread but @Rat Bastid how much if any does IFR size affect the transfer slot?
In case of IFR my understanding is that these restrictors deliver only gas so they can be rather small. In my case t-slot restrictor was not allowing the engine to pull right amount of gas in the transition slot which resulted in very lean condition.