Carburetor Standard Main Jet - 122-100 1INVENTORY Why don't the factory coils

Why don't the factory coils have these upgrades

Transmission Line Set For 58 Chevy Bel Air Biscayne Impala 283/348CID Engine 8 Cylinder Powerglide w/ Heavy Duty Cooling Stainless

which are only used for emissions reasons under light driving

1x Power Steering Line A

Carburetor Standard Main Jet - 122-100 1INVENTORY Why don't the factory coilsOverview: These metering orifices control fuel flow into the metering system. They are rated in flow capacity "cubic centimeters per minute" and are changeable for tuning purposes. The shape of the entry, exit, and size determines flow. All Holley Main jets are flow tested and then stamped with the correct number. Click on Catalog Product Page for complete listing of jets and sizes. Features: Fits All Holley Model 2010, 2300, 4010, 4011, 4150, 4160 &