I tore the muffler off Millicent a long time ago, making more room for water tanks and such. The increase in sound is slight. Healthier, but not loud. A turbocharger is an excellent "muffler".
Also, a long pipe dampens sound somewhat, even with nothing inside it. So you can take the edge off the sound by running a four inch pipe all the way to the rear bumper. But I dump mine in front of the rear tire, and I find it perfectly acceptable.