That model is a consumer saw with a "clam shell " cylinder .Meaning the cylinder and a portion of the crankcase is one piece .As such there is no practical way to raise the compression and other things normally done to pep up a saw engine .
You might try just polishing the ports but I wouldn't get real wild about altering them .That and relieving the exhaust pressure via a larger hole in the muffler is about all you can do to them .I wouldn't get real wild about that either because if I'm not mistaken they have a fixed main jet carb .
Like any clam shell Stihl they are designed as a consumer firewood saw and as such do very well .However although some of the owners rave about them they are not cantidates to be souped up .
Just do the repairs and cut firewood,it will serve you very well .
