On this parts fiche the Tube,air Cleaner Outlet is the most specified component.
The sixteen Gsx550es 1985 (f) (e01 E02 E04 E06 E17 E21 E22 E24 E25 E26 E34 E Air Cleaner component parts are all listed in this schematic.
The Air Cleaner is made up of components including this Cleaner Assembly,air which is the most expensive.