Last year I got my hands on a secondhand (almost) affordable S1R carbon fiber slip on muffler with a Can Am RT bracket. The darn thing was ear splitting LOUD. So, I went to work trying to calm it down a bit so I could hear my Sena headset, and still have the same performance and MPG. Here’s what I did. The previous owner(s) had obviously repacked the muffler and fractured the carbon fiber shell in a couple of places. Not too bad though. I drilled out the rivets and used a Dremel tool to cut off the damaged part of the housing. About a ½", not a biggie. Also had to shorten the baffle a ½”, if that’s what you’d want to call that thing. It does nothing but holds in the packing. Taking careful measurements of everything, diameter, length, and thickness, I ordered "can opener" style baffles to fit, and a 2Bros DB killer for the back end of the muffler. The DB killer kept the baffles from sliding out the back of the muffler. I had to order two different sized baffles because the front and rear of the muffler are now two different sized diameters. Now I had to cut and weld the two baffles to be the correct length to fit inside the muffler with no wiggle room. Everything I need I found on eBay at very little cost. Now to test it. Not loud but not that HD low rumble either. Just a hint of overlap on downshift and deceleration. Took a ride for 190 miles on the same loop as before with the same passenger and fueled up at the same gas pump. Got 40.5 MPG same as before. Didn’t test for acceleration because I don’t do that with a passenger. The modified 2Bros muffler weighed 6.5 lbs., and the stock muffler, 19 lbs. Now, if I’d just lost 12.5 lbs. myself, I wouldn’t have had to have done all that. LOL