what rear gear to choose for road racing

Regular TKO i agree. My liberty gears synchroed TKO shifts better than any car i have ever felt. Just my 2 cents. Maybe its comparing Apples to Green apples.

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It's not the good vs. bad shifting. It's the gear spacing/spread that's too far apart from optimal for most road course.

But what is the down fall of our factory style cone/clutch sure-grip on the track/course ?

Slippage, heat buildup, etc. We're talking sticky race tires that grip the pavement and don't slip like street tires. The less the tires slip, the more the wearable cones/clutches have to slip.