Dedenbear's optional Primary Throttle Kits are designed for extremely fast cars and / or engines with huge displacements. In applications demanding E.T. reductions of five-tenths (0.5 seconds) or more, this second set of Bear Stop butterflies and linkage is required. Unlike other kits available in the market, Dedenbear's Primary Throttle Kit was developed on a flow bench to maintain an optimum air flow curve. The resulting design effectively adjusts the geometry between the primaries and secondaries throughout the throttle travel, much like a progressive carburetor linkage. The Dedenbear Primary Throttle Kit fine tunes the Bear Stop's effectiveness and response over the entire throttle range.