Cold start Exhaust Popping

Hi ,
The previous owner installed Pod Filters to the carbs and this is probably the cause of an occasional exhaust pop up to about 2800rpm when at rest - nothing when revving higher - disappears at low revs when thoroughly warmed up - doesn’t seem to happen under load - only left hand cylinder.
Any other thoughts on issue - views on solutions, welcome!

Check the joints are all tight - exhaust flanges, carb inlet adaptors etc.
I had the same on my SP when I first put it back on the road. Not sure which was the culprit as I found a few things that needed a nip up.