A NAM Question (will reinstalling have a negative affect in my cities?)

[Mr_Maison]

I have some weird traveling going on in my region...(ferries going into cities that have no ferry terminals and Sims traveling through 2 large cities even though there's a highway and monorail going straight to their destination). I want to try to uninstall and reinstall NAM and choose perfect pathfinding, but I don't know if that will have a negative affect on my cities as they are now.
The region is made up of large cities only. The largest populated have around 700,000 residents and tons of commercial( a commercial city).