Next time you can try doing a pinch test. With a pump, you want to hear just a very, very slight increase in RPM when you pinch the line - like just enough so you know it's not lean. The pump will prohibit the engine from leaning out in flight and in verticals, so no need to richen your needle a few hundred RPM below peak as if you didn't have a pump - maybe 100rpm lower is all you need.

I like my tachometer, and find the pinch test works very well for me.