How does a Boost Bottle improve performance? Air rushes thru the carb on the intake cycle; ignition accelerates the piston down, forcing the reeds to snap shut. The momentum (inertia) of the air has to go someplace; it goes back thru the carb causing a double rich mixture. The result can be rough idle or hesitation.
Due to the high velocity of the fuel air mixture through the carb boot, you can take advantage of this momentum/inertia energy. The Boost Bottle Kit provides storage for the fuel air mixture between engine stroke cycles. The energy from KA Bottle Boost Kit forces the pre-atomized mixture in the boost bottle from the previous cycle into the adjoining carb boot where the reeds are just opening and ready to receive the fuel air mixture providing a "boost" supercharge effect to each cycle.
The Boost Bottle Kit is most effective at lower and mid-range rpm, and, when you are on & off the throttle. It assists in filling the cylinder (shorter distance) for a fraction of a second until the carburetor venturi gets enough velocity to fully atomize the fuel. The advantage is that it brings up the torque and horsepower in the bottom of the rpm range, up to where the pipe starts to work.