Ok, here is what i found best if you are going to shift the auto.
If you hold the shifter to the left for 2 seconds it will put the trans in the lowest gear for your speed and rpm.
If you hold it to the right it goes back to auto D mode.
If you are going for straight line performance it will shift at red line.
If you are in the curves or not full throttle, shift it.
Just my .02