is it safe to assume the car did not pull before the modification? Or not sure?

The wear on the tires can also cause a pull. Did the tires get tossed in a pile when they were taken off or were they mounted in the exact location as before?

If a computer alignment says the camber, caster, and toe are in spec yet the car still pulls then try swapping tire locations. That is what I used to do back in the day when I worked at Sears Auto to correct some pulling problems.