Welcome Tom,

What makes you so sure that the 12 inch setback helps with top end?

I would like to think it does :), and I have heard some amazing claims to that effect, from some boat and bracket manufacturers, but I am not aware of any truly scientific comparisons (controlled to a single variable -- the setback) for the v21, or any other boat or bracket. Not saying they don't exist -- just that I don't know of any. Maybe you could post a link to one?

Without a gps, your numbers are a bit iffy, as well. Although they do seem "about right".