Hi,
So I've been searching around and found a company that specializes in bracket for CTS-V swaps to Nissan and other cars:
http://ctsvbrakeswap.com.
The website is mostly empty but they do have a FB page
https://www.facebook.com/ctsvbrakeswap.
On their webpage they have a coming soon for BMW.
The price of CTS-V Brembo calipers is insane.
The 6 piston calipers are here (2009-2012):
http://www.ebay.com/itm/2009-12-Cadi...ac47f5&vxp=mtr
They support a 380mm rotor.
The 4 piston calipers are here (2004-2007):
http://www.ebay.com/itm/2004-07-Cadi...1a94dd&vxp=mtr
These support a 355mm rotor.
I would love to pick up some brackets and a pair of these with the right size rotors and get a monster BBK for $1100-1700.
Go to their FB page if this is interesting.