I agree that this saw may very well be down on power because of the EPA. The manufacturers made many changes to comply with the government regulations and smaller carbs, strato and restricted/cat exhausts may be part of the equation. If the manufacturer undersized the carb to meet emissions, it may be beyond the adjust-ability of the carb screws to get it up on it's power band. The strato system could also throw a monkey wrench in to the equation when it comes to adjust-ability. It moves a set amount of air into the cylinder each revolution and the carb has to account for that air. If the fuel circuits are at their limits, you may not be able to richen the saw up no matter how far out you turn the screws.