pipe popping

No cheap headers here. Dougs. No steering hitting either. And, no choke on a Holley 950HP.
I've been thinking burnt/cracked valve, too.............along with maybe some weird header gasket leak I can't find.
Also, I've never put a torque wrench on a sparkplug in my life and I ain't gonna start now.
I'm gonna have to figure it out soon cause I have other things that need attention. Moser axles, new driveshaft, etc.

Think I'll do a cold and hot compression check, then move on to pulling the header if need be. Can't think of anywhere else to look.