Oversize 390x32 https://racingbrake.com/2c70 - Available in 4-6 weeks, discs are ZR1 C7/Z28 rear (chopped carbon fiber)
Regular (stock) size 380x30 https://racingbrake.com/2c31 - Available ex-stock, discs are upgraded to RB's long carbon fiber and directional.
P/N 2C76 is for RB 4 pot caliper kit only and is not compatible with OE calipers.
Both stock size and oversize rotors retain OE drum emergency brake, having the same annulus (67mm) so you can use either stock pad (PD968 with 53mm depth) or ZR1 rear pad (PD1165 with 60mm depth).
A larger rotor provides longer torque arm (mechanical advantage) for more brake torque with the same pedal effort (force)
Edited by Warren-RB, 25 February 2021 - 11:07 AM.