light weight e34 M5 rear rotors

[ericono]

I'm in the middle of a brake upgrade and looking to see if anyone knows which rear rotors for the e34 M5 (300x20) are the lightest. I've seen images of some rotors that have holes in the hat portion of the rotor, but I'm not sure who makes those rotors or if they are even for this application.

Any help is appreciated.

Thanks,

Eric