After a 2-year long searching for both front and rear brake kits for my E31, I've finally got a set of custom-made GT brake kits from Brembo as my new year present.
The specs are:
Front: 4-pot F50 calipers with 355mm 2-piece floating rotors
Rear: 4-pot Lotus calipers with 345mm 2-piece floating rotors