Advancing Cam Question

Post #26 revealed what I expected & posted earlier. A little improvement in idle quality, but past that very little improvement that the butt-meter will feel. At the track, 4* of advance could go either way.
As D.Vizard says, only when an optimally speced cam is advanced or retarded will there be a noticeable difference; that is because all the selected components for the engine are optimised to work with the correctly selected cam & the most hp is produced. When the hp is at it's greatest, there is more hp to lose [ & for the butt-meter to feel ] than just any old cam.