I read MWeba's mods on the bigger 500 series brother not long ago. He claimed his breathed much better once he opened up the intake and put on a new filter. What I did was just poke a load of holes in my filter cover on the flywheel side to hopefully avoid too many fines getting in off the PTo side. I also added another exhaust vent on the flywheel side of the muffler as you can see in the pic. She is a much happier saw now.
Also, I gotta note that I like how the dB rating is an honest dB rating. I have a 281XP that says 102dB. Shyeah! Maybe if it had a rat stuck inside of the exhaust it might do 102...
With the extra exhaust outlet, this thing ain't an honest 116dB anymore tho...