I know numerous police chargers in my area had/have cam & lifter issues and had to have them replaced. These were cars anywhere from nearly brand new to about five years old. I don't know if its a metallurgy thing, oil viscosity thing, lubrication thing or what but one of the theories that seems to make the most sense to me is that at idle/low rpms it's not getting enough oil on the cam and lifters, partly due to the geometry of rockers/lifters. Between that and the MDS complications, it's eating itself up. The high idle times on police Hemis I'm sure plays a role in them tearing up.