My brother is doing a frame off resto on his 70 convertible. He has a 454 in it, with 291 heads. He had a set of headers on it with 2" tubes. He just bought a set of ceramic coated headers, but the tubes are only 1 3/4". He is worried that he will lose performance. He has a 3" exhaust with x-pipe and dynomax mufflers, and he just bought 2 1/2" mandrel bent tail pipes. Should he try and use these new headers, or try and send his out to get ceramic coated???? Thanks for any information

No he won't, the 1.75" headers are fine up to mild 500 inch motors..

I have a set on my 496, but don't have it in my car yet..

Same thing with reworked stock oval port heads, be them open or closed as long as they are true large ovals and the CR. and quench is OK..

pdq67

Cool, I'm sure he will be glad to hear that. He does have the 11.5:1 compression though. He built it years ago to LS6 specs