Fitting 08-10 Cobalt SS Brembo calipers to you og9-5 and ng9-3 is a great upgrade. …But and adaptor kit is needed!
This kit included specially machined bolts to adapt from m14 holes in the spindle to the m12 hardware needed for the Cobalt calipers.
ALSO! The calipers are not centered over the rotor when using the modified Cobalt rotors. Because of that, a shim in needed between the wheel bearing and the spindle. This prevents brake pad drag or rotor interference with the caliper.