Sound dampening Armstrong bracket

[bigbruse]

I have some harmonic noise in the cabin at around 4K rpm from my outboard! Can only hear it in the cabin outside of cabin you don’t hear it!
Anybody ever done dynomat inside their Armstrong bracket to dampen the noise from the outboard?
Thanks

 

[Bodick93]

Change RPMs? Easiest and cheapest solution, and I understand your dilemma. I always wanted to try a lower pitch prop, but never have.