Just to add to the confusion. I did a simple test on the dyno awhile back. My test was to see how main air bleed affected the timing of what rpm the booster started to flow. I tried various sized air bleeds and recorded the rpm at which the booster began to flow fuel. What I noticed was that regardless of main air bleed size the booster started flow at about the same rpm. In the last test I completely removed the main air bleed and the booster still started at the same rpm. I posted the results in a thread but I don't remember what thread it was. Maybe someone else does.