The butterfly shaft allows the butterfly closest to the barrel valve to open about a third of the way before the other two butterflies come off there idle position allowing for some part throttle driving which has proven to be a hit in the tractor pulling and endurance boat racing world or racer can pick to open the two butterflies furthest away from the barrel valve a third of the way before the third starts to open. This kit can be adapted to Enderle's Bird line of injector hats but should only be installed by a person with lots of mechanical ability.
Injector can be sent back to Enderle and for $125.00 they will professionally install the linkage kit on an existing Bird injector.