stihl 441 magnum not as powerful as i thought it should be?

an 046 magnum w/20" bar seems to cut better than my ms441 magnum w/24" bar using same style chains and both brand new (the chains and bars). Sometimes my powerhead seems to bog down. If i put any pressure on the saw at all while sawing firewood the saw seems to lose power in 16" logs

Lucky Lynn
May 2009