The city could try making traffic more friendly for the affected neighborhoods. They could build traffic calming impediments on the “wide streets”, such as concrete pedestrian crossings that create narrow gaps, S-curves, roundabouts, center dividers, all kinds of immovable changes that would make a road useless for a drag race.
Yes, I know that LA drivers really want the traffic to flow much more than they care about the houses they drive by, but maybe the city needs to change that and start protecting the residents.