The 335i uses GA6HP19Z gearbox.
GA6HP19Z (designed for maximum torque of 400 Nm).
I think abit more than torque limit isn't too bad, just increase the wear and tear of your gearbox. Depends on how old your car is and how hard the previous owner abuse the car, i would consider slowing the mods down. "Only if you plan to keep the car"
With that said, i am yet to find anyone who screw up their tranny due to torque increase.