Originally Posted by Beitsta
My problem is that she will only rev to 5,000 RPM
If the engine was mounted too high, I'd expect it to over rev and cavitate.
There are three fins on the Suzuki and the antivent plate (bottom one of the three) looks more or less level to me. Level with the keel is only a rule of thumb anyway as lots of ribs (Ospreys included) run with the plate 1"-2" above the keel line.
To find the extra 1000rpm I'd try a 17" pitch prop, more out-trim when on the plane or better balancing of the boat before messing with the engine height.
Also those transom add-ons look like they are set too low.