I have two outboards for my boat. A Mercury 4.5 short shaft, and an Evinrude 4 long, both two stroke. The Merc is damn heavy compared to Evan, but you notice that half HP for sure. The long shaft tends to drag the water, but the weight off the rear is noticeable also. So, for what it's worth, Knowing what I know now, and where I sail (Monterey Bay), I can say without a doubt that....it's a total crap shoot. The 4 will be better for racing as I can easily get it off the mount to store below. The 4.5 for when the wind picks up, and it does. Let local average weather conditions dictate motor selection on your next purchase.