Michigan-based Kustom Headers became the supplier of Z28 headers to GM starting in 1968.
I don't know if it was based strictly on cost but certainly that probably factored into the
equation. The most high-profile team to use Kustom Headers were the "Chaparral" Camaros
of Jim Hall.
Close-up view of a GM part number on the header flange. For some reason there are a few
different GM part numbers for these Kustom-built headers. These were also available direct
from Kustom and those are stamped KH-37 on the flange.
Some Kustom header flanges are squared-off on the ends and some are pointed.
There does not appear to be any clear reason why. Note the 4-bolt collector flanges.
Info provided in the '68 Z28 brochure. Note the different part number(s).
From the 1974 Kustom Headers catalog...
Here's Gene Harrington's '69 T/A camaro sporting a Kustom Headers decal
on the front fender, behind the front tire.Photo: Mike Jarchow Collection