There should be a "highShiftUpRPM5" so you can say okay, 1 - 4 shift up at 2000, and then when 5th engages at 2300 to help with torque converter tuning!! I find it very difficult, and think that for modders this would be very helpful.
This IS something useful if you have odd gearing and your torque peak isn't in the end of the RPM. However you can also figure it yourself with the peak torque and the gear ratios using maths.
I was going to use it for making it so the torque converter locks up when I want it to. It stays locked in fourth, then it goes to fifth and then its unlocked and all loose. I would have it shift at a higher RPM so it DOES stay locked when it shifts. But what do you mean using maths...?
This already exists, just treat it like the other shift points and make an array like "highShiftUpRPM":[0,0,4500,4000,4000,3800] for example.
I thought you mean manual, since with autos you cannot get the gearing. But assuming you can get the gearings for the gears, the differential, and the torque curve, you can use math to see how each gear's torque interact with another gear's one, and finding out at what exact point you should shift.
No, it refers 1:1 to the gear ratio array, so the first entry would be the reverse gear for normal cars, second is N, the third is the 1st gear and so on.