I am wanting to tune the focus routine in voyager to see if I can get a better focus. What settings can I tweak for tuning?
There is no autofocus tuning, what you can do is solve any focuser problems, such as implementing backlash management, or bypassing the limits by applying a reduction to the gears if you have too low a motion resolution. In some cases it is necessary to control slippage by checking that you have not applied too much weight or by adjusting the clutches.
Voyager side, if you use the focus on the single star (not the localfield) you can add more VCurves and eliminate the low quality ones.
Keep in mind that the autofocus is equipped with AI so over time it continues to adjust in terms of execution parameters.