Depending on the year and model of the attachment points are different.

Front and rear bumper removed along with the metal amps

Front bumper

To remove the front bumper, need to screw through the openings of the fog light the screws holding the amplifier to the bracket. Next, Unscrew the screws around the perimeter of the lower part (if any). Then release the fastener and wings. Depending on the year these will be either screws or slides.mounting points for the front bumper Alfa Romeo 164

Rear bumper

Depending on the year, you need to either Unscrew the screws holding the amplifier bumper to the brackets (from under the car, spun bottom-up) or from the trunk remove the screws that attach the brackets to the rear panel. Then Unscrew the screws that attach the protection to the lower part (if any). And in the wheel wells, Unscrew the screws that attach the angles to the wings or free the slide.

mounting points for the rear bumper Alfa Romeo 164

mounting points for the rear bumper Alfa Romeo 164

rear bumper mounting scheme Alfa Romeo 164

rear bumper mounting scheme Alfa Romeo 164