Exhaust Manifold

What is the purpose of the "flap" in the exhaust manifold? Can it be removed?

There is a passage cast in most intakes that lets hot exhaust gas run under the Carb to heat up the carb when the engine is cold. The flap is attached to a metal coil that closes the flap when it is cold and opens it when hot. When cold (closed) it forces exhaust gas up through the intake and into the opposite exhaust. Unless you are doing a by the numbers restoration cut it out and weld up the holes! Even when it works some heat goes up into the intake. Colder intake mean denser fuel and more power. Many performance intakes don't even have the crossover. Even a basic Felpro gasket set has an extra metal intake gasket with the crossover blocked off.