Key here is finding a Roush dealer..Such as Sayville Ford on L.I.
Also when resale is considered, Roush dealer is key
I heard of two stories of certified roush Ford dealers saying no to replacing the motors of roush vehicles with blowers. Ford would not warranty the work so they went to roush. Roush said no a few times to each party.
One belonged to the owner of the dealership who knew Jack personally. After hearing no go on his warranty through roush corp, he called jack personally. Only then did he get his motor replaced. The other guy was out of luck.