I notice that my 445 would get really hot after making a few cuts. I assume it was set lean from the factory so I drilled three 3/16" holes in the muffler and backed the H screw out a 1/4 turn. I can't say for sure if it cuts any faster (stock chain) but it sure runs alot cooler. also, the small holes didn't seem to make the saw any louder. I wear ear muffs anyway