I just bought a 2008 M109r2 with a Sideburner exhaust. It's too loud and want to quiet it down a bit. Thinking of inserting the following baffles in the head pipes before the collector- Thunder-Monster baffles
They calm it down some, but they are still pretty loud. Over the years folks have tried those, and the Smartpartz baffles, which might actually be the same baffle. At least a couple have made their own. In the link below the first baffle that Josh made I've actually heard, and it wasn't too bad. Might try that if you're handy with tools.
I bought the SmartPartz Baffle, and it fell out after one ride. Instead of spending another $60 for one, I make one for less than $15.00. I bought a 4 inch Galvanized pipe stand. The base measures 3 7/8 inches in Diameter. It barely fits in there. Then there's a 1 inch x 4 inch section...
You can also do a search at the top of any page to get more ideas. Just search for "side burner baffle".
Really all you need to do is make the outlet opening itself smaller. You could make something temporary out of sheet metal to test opening sizes for power and sound , then find something more permanant.
I created the home-made baffle. It seems to work well. It took the edge off the loudness. Still louder than what I would like. Maybe change to cobra swept pipes or Vance and Hines. Any suggestions for quieter aftermarket pipes?