Totally agree about headers and heat. Some coatings are to protect, some are for heat. The heat protection is the expensive type. I have had headers on about everything I have owned and made a fair number of them. Even with just plain old steel headers, heat radiation wasn't much of a problem if the cooling system was working right. I took the set off my '37 and went back to cast iron manifold, guess I am getting old because the noise was bothersome. Thin walled headers make a lot of noise, and it's not out of the tail pipes, you can hear each cylinder fire or ping through the pipes. With the close quarters of the '37 cab to the engine, along with the open cowl vent, it was like setting right on top of the exhaust system.
I made some test run at the local drag strip with and without headers in a two week time frame. With low rpm and measly 110 hp of the 250, headers made zero difference, not in mph or ET. I used the same 2" muffler and tail pipe, head pipe was 2" with cast manifold, 2 1/4" with headers. RPM had little effect on the out come.
