Hi
I doubt it will be possible to make the 94 dB limit with a prop like the 18x10 on a YS 160. It sings out loud ! The good news is that we all, are going to be measured to the level of 94 dB OVER ALL SURFACES ( So it is, as I recall from the latest CIAM meeting ).

We have measured some of the YS 160's in my club and none makes the 92dB, but they make the 94 dB limit. That is, with 17X12 or 16½x13W or 16½x12w APC's. And the latters make the noise limit but they are, as Ola says, a little difficult to handle.

On another note :
But actually we are facing a silly old rule ...We are not going to go full speed very often, or very long anymore, with the power we have at hand .....so why not start measuring the noise according to revolutions on the motor ? Since we know it is not good to go full speed all the time as the pattern will suffer from this, the right thing would be to measure the noise from an aeroplane going exactly say 8000 rpm and then score it from 0 to 10. That would be something new...