Backfire on deceleration?

vegasanthony said
So ive been running my 2000 5.9 magnum efi swap for about 6mo and i recently started getting backfires on deceleration..
Ive been reading on a causes of this..
Exhaust leaks seem to be one reason
And running lean another..

So my question is would a Exhaust leak near the header make it backfire
So badly near the muffler or should i start diagnosing at the fuel system
Seems to be drivers side only
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usually, if you have open headers or manifolds it will pop out of the exhaust after running at a constant rpm; say 4000 after a little bit. I have a '73 318 in my duster with a carb. However, these pops are pretty small and wouldn't blow out a muffler like that. https://photos.app.goo.gl/Fr6RZLNPnryJoTh16
I wound not call that normal especially for EFI and a new magnum like that. more of an old school thing.