3-4 shift times are zero'd in every tune I have run across. I set the command shift times for 1-2 and 2-3 to 0.300 seconds. I use 40% torque reduction flat across the 1-2 and 2-3 shift. I also use the Tow/Haul line pressure map out of something like a 2002 5.3 Tahoe tune. The result is a firmer shifting trans with less slippage and cooler running. I also make a change to the pressure control solenoid map. I zero the 90 "psi" and 100 "psi" lines.
If you zero out or reduce the torque management you will cause the trans to slip during shifts and eventually cook it. You want the trans to shift quicker and cutting more power during the shift helps accomplish this along with the higher line pressure and shorter commanded shift times. The torque reduction is only in effect for the length of time of the commanded shift time. Here is what a stock 4L60E with Sonnax Superhold 2nd and 4th gear servos shifts like with the settings above. The real sharp snap you hear during the shift is the out of the exhaust due to the engine running at Zero timing advance for the 0.300s of the upshift. The shifts were very quick and crisp and not soft, delayed and sluggish like the stock setup yet not overly firm either.
Performance mode is Tow/Haul and they cut more power when it is in Tow/Haul to help keep the trans alive under the abuse of towing. More power being cut equals less abuse, less clutch slippage and cooler trans temps. If you look their is also more torque reduction % in Performamce mode.
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