I have a set of brand new OEM 35iS/Euro rear calipers for sale.
35iS rear brakes are the only upgrade rear brake available for US 28i/30i/35i (And all euro non-35i/35iS)! It should fully work with the electronic parking brake
Upgrading your rears is key if you want to maintain brake balance.
I have the calipers and caliper carriers for sale. I bought them new from the dealer to install on my car, but ended up selling the car before completing the setup. All you would need is the 35iS rotors and pads, though my research shows the pads *may* cross over actually, but I have not been able to confirm it.
The calipers cost me over $1350USD, you can price them yourself at your dealer and see what I mean! Edit: BMW changed the price on these parts, now its over $1500 to replicate!
New Price: Priced to move at $800 shipped!