take the muffler face plate off, follow though the heat sheild with 1 hole, maybe two using the same size bit as the holes in the heat sheild, remove all the burs from the inside of the face plate and reinstall. ( I drilled out the hole in the center, looking down from the top of the saw angling to the left). expect about a 20% power gain. not speed, power . Oh and remove the screen and the tiny scew holding it on... And then screw the carb adjustments all the way in and then out EXACTLY one turn or one turn and a quarter, some stickers on the saw near the adjustments will tell you how much to turn them (out) or counter clockwise for more speed. I hope this has helped, enjoy the new found power