I guess the aftercoolers put on every turbocharged vehicle available today are just extra parts then-
Just because the manufacturer felt they could get the car out of warranty without one does not mean it's not needed. I remember my Trooper TD needed one badly, even with new radiator, water pump, and thermostat the coolant temp would jump on hills. Much of this was due to the lack of charge air cooling, I verified this by running for a time without the turbo. The temps hardly got into the operating range, even though there was quite a bit of smoke showing sufficient fuel.