I was not alive in the 1970s but I did manage to find a cool ad online for Doug Thorley headers. You can see they're black here. I have Appliance headers on my Camaro and had them done in white. They're ceramic coated... It's holding up ok but not perfect. I probably have about 500 miles on them. Cylinder number three primary showed some white flaking off after about 200 miles. Sort of disappointing considering it's not running lean but what can you do? I'm not planning on taking them back out
I know Doug's and Doug Thorley's are two different makes, I believe Doug's stayed with Mr. Thorley and his ex-wife went on to make Doug Thorley headers. I think the story went something like