I find I get a grease build up on mine from whatever Rivian assembled the brakes with. I also think the paint is pretty thin/cheap on the calipers.
if iron remover doesn’t clean them you can try some polish by hand. Something mild like Meguiars scratch-x should remove it easily.
Since I swapped with season change it’s hard to compare but my efficiency is much better with this setup. But the temps are probably the primary influence there. It does ride better vs the OEM tires on OEM 22”wheels.
I use an electric impact for removal only. It's habit because I had a lift at my old house (building a garage at new house to install the lift again) and once it's lifted, its the only way to remove without someone sitting inside pressing on the brake pedal.
I install by hand only and torque...
To answer what was not previously answered above:
They are plain smooth black but came with the KAOS stickers that could be applied. You can see them in the photos on the S00nish site. They (stickers) seem almost like they have a metallic layer. I did not install them as I am looking at getting...