My 04 Fatboy has 47,000 miles on original Vance and Hines big shots long, high flow air cleaner and H-D race tuner kit. Exhaust now pops when closing the throttle at 75 miles per hour or less. Use to be just the normal rumble on decel.

Are the baffles worn out or do I need a re-flash with the race tuner?

 

Check the fuel pressure. Intake seals. Exhaust gaskets.

 

Really take a detailed look at your exhaust too...soot and/or hissing = leaks. All it takes is a pinhole to make issues appear.

 

Make sure the butterfly is completely close when you let off.