Think of the air passages (they're called air "bleeds") as timing devices. They control when the transition is made from one circuit to another. In our application, we're working around something designed for a completely different application than what we're using them for. Luckily, we can normally work around it with jetting because for the most part, we are above the rpm it was designed for and we are on both circuits all the time versus transitioning from low speed to high speed like going from idle to wide open or coming on or off of the governor. Is there something to be gained? Always, but for most stock class engines, you'll see little to no gains maxing out the air bleeds because we stay mostly at wide open throttle and high rpms and stay on both fuel circuits pretty much all the time. It takes hours of dyno time with a very consistent dyno and proper equipment to monitor EGT and Air/Fuel ratio to get them spot on and for the most part, we find it better to verify the factory bleeds are at a consistent size and focus on controlling the Air/Fuel with jetting, throttle angle, and E-tubes. Good Luck!
