"Ron Rosenfeld" wrote

I notice that on my turbo-normalized, manually waste-gated engine, too.
As
a matter of fact, if I'm climbing into the low teens, and maintaining say
25/2500 during the climb, at my target altitude, decreasing RPM to 2400
RPM
will usually drop my MP by 2-3" or so.

That would logically follow, since when you reduce RPM, you are putting less
volume through the turbocharger turbine, and that will slow it down, and
give less pressure to the intake manifold.
--
Jim in NC