Hello Paula,

Welcome to the forum.

You will have to help us- help you on this subject.

The Beta 43 uses 2" exhaust hose. Typically you can do the whole run with 2" hose from the exhaust elbow to the 2" exhaust thru-hull.

Muffler selection is not so straight forward. The muffler must be fit to the engine, the hull space and also the exhaust hose run . A muffler that works in one vessel powered by a Beta 43 may not work at all in a different vessel.

Please provide a bit of information about the vessel you are re-powering.

What is the make of the vessel?

How long will the hose run be from engine to exhaust thru-hull?

We may ultimately ask for photos in order to better understand the exhaust system you are installing.

For reference, basic exhaust system design can be found at this link to the Beta Marine, Re-power Centre. http://www.betamarinenc.com/index.php/repower-centre/exhaust-design