Have an 064 and ms660. I do think the 660 DP muffler, has more torque. Since I've had the 064 I usually run an 28" bar on it and does feel like out standing balance and reach with that combo. Significantly more torque then my previous 046 which I sold. Its pretty stout to pull but since I learned to listen carefully for the pop ( when I first got it I missed the pop several times and flooded it ), usually it hits #2 or 3 pull, then 1 or 2 more to start. I have a rather lame shoulder, but it seldom bothers me to start it. I've had more problems with smaller saws at times. No problem with vibes. Sometimes a slightly bent handle bar or other structure defect makes a saw vibrate to the hands.