Mate your cav plate should sit level with the bottom of your hull, and the stingray should run on top of the water. I have fitted one for a mate and he was happy with the height of the engine but the stingray was under the water so I fitted some pieces of tube between the cav plate and the foilto get it level with the water and this helped reduce the spray.The stingray will put out some spray but this is not really an issue. You should notice a significant improvement getting on the plane (assuming it is a tiller steer) and maintaining a lower speed plane. I think you will be impressed when it is set up correctly.
Thanks
Lee