There has been a lot of differences in the thickness of the fiberglass with the CR. That probably accounts for a lot of the weight differences. Mine is quite thin in sections. Across the rear deck it was only 2.5mm thick. I added another 3 layers of Kevlar mat to stiffen it up.
Fired up the lathe this evening and machined one of the 2 piece brake rotors. It looks as though the hat section was originally machined from a disc rotor as it's cast iron. Cast iron makes a mess when you machine it.
I'm just truing it up here prior to modifying the lip on the back of the hat so it fits into the ford backing plate.
The rear lip turned out fine and I've machined the outside of the flange to fit inside the rotor. With the rotor bolted up to the hat now the offsets are near perfect. Just got to re-drill the stud pattern so I can bolt it up and check the fit with the caliper.
Cheers