Marty how high is your transom. Bottom transom junction to top of transom?
Have you used an OB yet? My exhaust port on the cav plate was at times out of the water unless I removed the fwd ballast. Just a big jug of water. Sunchaser was trying to keep me from making a mistake cutting down the transom 2". I plan to call Gig Harbor boats about it but haven't yet. Thankfully my gunwale is plenty big. Only two small vents too.
North Western Washington State USA