Do you mean changing first gear to a higher ratio?
They sell a 2.84/ 1.55 first second gear ratio set which makes for much more friendly launches if you drag race. It makes first gear longer and avoids the drastic gear ration split on the 1-2 shift.
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2.84 Ratio Input Carrier Kit - 77284-K
Ramp up from OE wide ratio to race-ready close ratio. Keeps engine power band on 1-2 & 2-3 shifts. Fits 4L60-E, 4L65-E, 4L70-E. Part No. 77284-K