There’s not a whole lot of support for the Mazda 323 GTX here in the States. Which is why I ordered a ramhorn turbo manifold from a guy in Malaysia who makes them.
Ever since the 2.5" turbo-back exhaust was installed, the car has been overboosting in cold weather. An external wastegate should fix that problem, and the stock turbo manifold is notorious for developing a crack where the O2 sensor is. Two birds with one stone.