When you mount the transducer, do you want it flat with the bottom of the boat or tilted up with the nose slightly down?

i mounted mine assuming it would be level while the boat sat in the water. i used the water stain on my boat as a guide.

You want the transducer to be level with the water surface when you are using it. If your boat has water line stain on it, just align it with that.

For proper operation on the transom while on plane, most have to set the trailing edge a little lower than the leading edge to avoid air bubbles over the face. Set the height of it just like the included instructions.