As to the Mixing Elbow
.. I have 2 Stainless mixing elbows that I had made for my boat, but can't use (MD2030). Turns out I needed a rising elbow
and had regular elbows built. The were made by the ExhaustElbow.com
fellow and are good quality. Should last the life of the motor
I could sell you one at a good deal. Shipping
to Aus shouldn't be that much. Let me know if you are interested and I can send you some pictures.