Anyone out there know what causes afterburning in a header? I run zoomies on my alcohol buring BBC and experienced what others called afterburning in the pipes. It looks like that may have happened by the color on the pipes from the flange to the bend. We were fat on the tune and were dialing it in when the weather turned on us at WOS. I got to thinking, dangerous, alcolhol burns cooler so if raw fuel is getting into the exhaust header how does that cause afterburing if the pipe is cooler as well?