After driving/testing for a week, I've decided that my hydraulic system is OK. My pedal never goes hard and the system is even under pressure after 30 hrs. I can push 55x my break pedal after 2 hrs stand still.
The 'bomb' pressure is 50 bar and the switch triggers the alarm at 80-100 bar. The pump delivers 147 bar. All within the specs.
If anyone needs advice on the brake system/hydraulics, feel free to sent me a PN, and I will try to help you out.
Conclusion: 2 AUDI dealers totally overlooked this problem (I damaged my front bumper once...), the 3rd helped me professionally. But could not measure the hydraulic pressure.
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