The manifold can get REALLY hot and that is why I believe the heat riser and the butterfly valve are on the original exhaust manifold. It is also a cooling effect. That's why I like water. It heats but also keeps things from getting too hot. A very consistent 170 degrees. Exhaust heat from Fentons doesn't have a way to turn off the heat once things get warm. On the other hand, how much heat gets through those tubes anyway? I'd bet it gets above 170.
