That is one hell of a difficult question. Do you want temps at idle? Temps after a few hrs of running the car, Temps if the car is in Fl , ,Alaska, New York etc. There is no firm answer for a question like this you have to be specific as no 2 cars run the same. Your best bet is to buy or borrow a friend's infrared temp sensor aim it at your j pipe and take a reading this way it will be correct for your car.