I'm still running the standard gearbox, it's an Edward Lees special edition with close to 500k kms on it lol.
It's done 1x track day with the new motor and has exploded yet, has done over half a dozen track days with 372kW before the old motor let go.
I rarely smash it into 3rd hard, because it grinds every time above 7k rpm, so I need to literally ease it into 3rd when I shift and make sure I'm under 7k rpm.
I wonder if you were also running the wrong bearing carrier which caused the throw out bearing to be riding on the pressure plate