Stock cars are getting transmissions warrantied for excessive syncro wear.
400wtq will shear 4th with street tires everytime. I did it with 460whp 393wtq in just a few thousand miles on hankook ventus v12s. Not a grippy tire.
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Synack sheared 4th with only 350whp I'm not sure his torque. He has stock suspension and 19 inch wheels. So he can't have too much grip.
My first transmission the syncros died. Not power related at all. A faulty part.
My second transmission had bad syncros as well and I sheared 4th while in boost.
My 3rd transmission that's in the car now is a used one with 19,000 miles and shifts smoother than all the others. I've put 1000 hard miles on it and it hasn't broken yet. With stock fluid in it.
The box is very very weak.
Element tuning blew one up at around 400 hp and started running a cooler. I'm running a similar setup now and it's thermostatic but I haven't gotten it hit enough to turn on. It's been in the 30 and 40s here with cold slippery pavement. I don't think it's going to do much good honestly.
I'm well educated in every available transmission swap for this car.