If your mating surfaces are fairly flat a coat of Red Hi Temp RTV only will do the trick. If the flanges are warped the Remflex is hard to beat.

Either way Remflex are hard to beat but Red RTV is cheap and works well in most situations.

Regardless of any gasket manufacturer or material, the final matter is how the mating surfaces are from the header flange to the gasket. I've seen more poorly designed header flanges that will not allow any gasket to seal, and the RTV eventually will blow through.

Mate the gasket to the header flange and determine if there are passages -- even very slight gaps, such a 1/64" or progressively larger -- for exhaust leakage. Raised ridge/beads are the most concern (example: Hookers). If needed, apply a wide-spread amount of JB-Weld Extreme-Temp putty around header flange, allow one-day to dry, then flat file the surface to be flush... in other words, a wider flange surface that will mate with the gasket. That' what I've done and had excellent success.

MOPARXs solution is the trick, it allows each port's flange to conform more readily
to the head without being restrained by the other port flanges.

When you cut between the middle and end ports you'll see how the tubes then take a new
plane.

Try it, you'll like it....

Joe

Filing the welded bead headers with a large file works nice as well. Just ink them up and file lightly in multiple directions until the ink is gone. The wider the file the better.

remflex here as well

Remflex are THICK.... moved my headers enough to contact my steering. Nothing a little “ding” didn’t take care of, but something to think about.

Red Sensor safe silicone...…

Best "gaskets" I ever used

LMAO !

I'm not a SBC guy but our endurance car is a GM product. When we were installing the headers I went to get the gaskets, my teammate (ran roundy roundy chevy's a long time) said what are you doing. He grabbed a tube of silicone and said this is all you need. And SOB we have 80+ hours of hard racing and NO leaks.

I stopped using header gaskets a long time ago....they always leak at the worst time.
Red Silicone for the win ! ! !

I only run the aluminum ones. https://www.jegs.com/i/JEGS/555/212555/10002/-1

The only time they blow is if the bolts shake loose. Usually need retightened a few times after install.

They are thick so may need slightly longer bolts.

I have re-used them up to a half dozen times.