I nm adding CMI headers with Cmi tailpipes and Livorsi Bandit mufflers as far as I can see there is no flapper in these parts whare should it be or do I need the external rubber kind I am pretty flapper iliterate

bump

Use the external rubber model. When you are shut down enjoying some sun or lunch there is always somebody running a wake into your transom. Without the flapper you get an engine full of water.