I am trying the needles at the fourth notch from the top. (it seemed like the easiest and least intrusive step) I have only done one static test run. I ran the engine for ~ 15 minutes at various throttle setting (sometimes at 5600, the prop wash was impressive!). I slowed the engine down taking ~15-20 seconds and shut it down. After I let the engine cool I checked the top 4 spark plugs. Front plugs were sooty. Back ones slight color to white. Before changing the needle all the plug insulators were white.
I will be doing flight tests when the weather gets better.