With a full length panhard bar, the point where it crosses the centerline of the car is the roll center height. So moving it up and down changes the roll center height which changes the roll couple (roll resistance).

So the height you put the panhard bar totally effects roll.

In Nascar Cup when they move the "bar" up and down (a short J-bar panhard bar) they are changing roll center height and changing oversteer/understeer