Exhaust popping

[svsteve]

Looking for some thoughts what might be causing popping from exhaust. It's been doing it for a while. I thought doing de-smog might help, but it didn't. It has been doing it a bit since I did glass packs a bunch of years ago, but seems to be getting worse. Its mostly on deceleration, but now I here it pop now and then at idle. Any thoughts.
TIA
Steve

[Hook#3287]

What did you use to plug the intake nipples?  Are they still good?

Could be a number of things, but checking for vacuum leaks would be my first thing.

[..]

And snug up the small header bolts. BE GENTLE WITH THEM.