I did find a brake upgrade!
It's a Brembo GT brake upgrade kit, but brembo say's that they only have the kit for models 528i and 535i.
So they told me that they didn't know if it would fit my 530d because it wasn't tested yet.
So I went on a little search and I did find out that brakes on the models: 520d, 525d, 530d, 523i, 528i (touring and sedan) are all the same.
And brakes for the 535d, 535i and 550i (touring and sedan) are also the same.
I've got a price by e-mail, it was:
€2512,50 for 6-piston callipers and 365 x 34 mm disc's ($ 3675)
€3037,50 for 6-piston callipers and 405 x 34 mm disc's ($ 4442)
Excl. VAT!
I'll let you guys know what I'm going to decide and I will try to find part numbers -)).