Two-Piece Rotors

The dust in the rims is from pad design, the original pads are a softer compound then whatever your friend put on clearly but as for working just as good, you maybe won't notice on the street but on the track you sure would, the 2 piece rotors dissipate heat better than a single piece rotor and in turn help with brake fad after hard braking like on a track but they are dam expensive for sure