Running gear design issue.......

Been thinking (dangerous);
Your original hp was 220 at so many rpm. You have this new engine that is spinning the same wheel size (same wheel?) and now your spinning more shaft rpm. Also noted; going faster.
Could operating beyond original specs contribute to a high rpm vibration?

Thoughts on this; Wheel diameter clearance to hull? Strut torsion? Mounts flexing? Shaft twisting? Air on wheel tips and cavitation? Turbulence on rudder?

Just some ideas, Please let us know what you find.