I've stripped 2nd, 3rd and 5th, broken diff bolts (might not have been root cause), CV joints.... basically mashed them up.
Serious power needs either a bespoke 085 (Gemini etc - but still torque limited), Sadev/XTrac etc if you want sequential with torque capacity or bolt a larger Golf box on with adapter plate & chassis mods.
No simple fix, the gearsets which you can get aren't rated for serious amounts of torque, and any post manufacturing processes to treat gears is highly expensive and IMO unproven on an 085.
You can do an 085 > 02J conversion for about £1k - the boxes are dirt cheap and the range of aftermarket parts is plentiful, gear kits, gucci shifters, LSD etc.
