chris writes:

Are you perhaps pulling the RPM back too much and seeing a decrease in
airspeed?

The redline RPM is about 2500, and I pull it back to about 2000-2200.
My IAS then drops by 10 kts or so. The engine is less noisy. I don't
adjust the throttle (which in most cases is fully forward) or mixture
(adjusted for slightly ROP). The fuel rate drops a lot with the RPM,
but the manifold pressure doesn't seem to move much, or I haven't
looked at it closely enough.

Takeoff and landing of course are with the prop set to full fine

Yes, for take-off and landing I make sure the props and mixture are
set fully forward again.

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