Lots of parts for our bikes were made by other manufacturers..
Horn- Mitsuba
Wiring Harness- Sumitomo Electric
Alternator Coils, Voltage Regulator, Rectifier- Hitachi
Gauges- NipponDenso, Nippon Sakei
Rims- D.I.D. (can't remember the words in the acronym.. Daido something)
Sparkplugs- NGK or Denso
Control Pods, Ignition Coils and Points- TEK (Tokai Electric ... ?)
Battery- Yuasa
Lights- OE Stanley
Mufflers- Sankeii (stamped on the back of the later rolled mufflers found on the 750 and 550)
Brake Calipers- Tokico
Key Switch- Niles (No longer in business)
Carburetors- KeiHin
These are all items I've seen manufacturer names on. Other items, such as filters, were likely made by someone else too..
So, the pipes could have been made by the company that once supplied them, but not directly through Honda. This then begs the question if they are doing this with Honda's permission.