Speed displacement graph:
I'm gunna up the Y-scale of this, its way too flat (so this is a preview). Feel free to update it.
X-axis = the speed value for $7E007B and $7E007D
Y-axis = how much mario is moved in pixels per frame
So basically, what is happening is that the line is 2 pixels thick on x-values not divisible by #$10, this is because the position doesn't get added/subtracted by the same value each frame. Thus representing the possible Y-value range for inputting the speed value.
Give thanks to RPG hacker for working on Asar.