Everything about the CB350F was about saving weight to counter the small engine. Even the exhaust pipes and mufflers just weighed in at 25 pounds. Honda used very thin metal on the muffler part of the pipes to save weight, and they didn't last long. I'm guessing that these are aftermarket and OEM's are very dear to unobtainable.
Gianni is Daily Turismo's Pacific Northwest correspondent. The Seafair Pirates were (still are) always his favorite part of local parades.