Race muffler and K&N filter, new plugs, cleaned injectors, recently re-gasketed engine.
I had a burn out Jardine that I bought the bike with; so far the OEM race muffler is superior in my opinion. Just yesterday someone walked up to me after filling his car to tell me how good it sounded coming into the gas station. I was filling my tires at the time.
Regardless, here's a video of mine. I think on my channel I have a video of it idling with the ****ty burnt-out jardine.
https://youtu.be/fC45iCWp1vU