Any muffler would restrict the exhaust and being a 2stroke just minor restrictions can drastically change the power characteristics of the motor. 2stroke dirt bikes, quads, and snowmobiles have crazy expansion chambers before their mufflers that give the motor it's power characteristics, and their design is complicated.
I myself have a model 30, and I am big on utilizing ear protection when I shoot, at work when i'm using a hammer drill or something else loud, and in the back yard when using loud equipment. I have used ear plugs on the ice, but it's annoying putting them in and then removing them, etc. Now I generally just wear a good hat and pull it down over my ears (wind proof hat material has good noise reduction properties) and also put my hood on and snug it down. I also sometimes will keep my snowmobile helmet on, does the same thing. I know there is no NRR rating on my hat and hood, but I feel it should be good enough for most.