YS on the test stand vs in the plane?
From my past experience with YS engines, Yes, they are pretty close given that you are using 20% or above nitro. Lower nitro fuel did not work well in plane compared to on stand.
I set up slightly rich on stand. Most of my engines stayed within 1/4 ~ 1/2 turn differences. All my YS engines were installed inverted, in-cowl.
Hope this helps,