Alignment setting have an effect on all of this as well. If you have little to no positive caster, the steering will seem nervous and flighty, especially at speed. Adding more positive caster will improve the stability of the car, and can increase the steering effort some.
It’s a different effect from the amount of boost provided by the factory power steering, which is quite overboosted and gives very little feel. That’s addressed better by reducing the pressure. But that should just feel like the steering effort is very light, it shouldn’t feel like that car is unstable or erratic. That’s more likely worn components or a lack of positive caster, or a combination of both.
