The biggest reason why I don't like the tube style heat from each header to the plate under the intake manifold is that it deadens the crisp sound of the exhaust. The tubes allow the exhaust from each side to be mixed, thus deadening the crisp sound of a 216-235-261. The tubes become equalizers for the exhaust system. The headers with the built in heat box keep the sides separate, as does the water heated method.
Joe
