I think it varies from car to car and according to comfort level. If you put 5-10 PSI in both bags it should help you with body roll but just experiment to see which way it rides the best and controls the roll and set it there.
Due to the many varibles on the street, I'm unable to see an advantage with any settings different than at the track. I just don't think any one setting will be just right everywhere on the street.
I'm just going for a larger sway bar.
