Depending on the year of release of the attachment can vary.
Front bumper
The bumper is held on two bolts. Take out the repeaters of turn indicators, and detachable connectors. Unscrew the two bolts (spun upwards) that secure the amplifier to the body. With the assistant pulls the bumper with the rails in the wings forward (look for wires). Disconnect the electrical connectors (if any).
Rear bumper
Is attached as well as the front. Take out the repeaters of turn indicators, and detachable connectors. Unscrew the two bolts (spun upwards) that secure the amplifier to the body. With the assistant pulls the bumper with the rails in the wings forward (look for wires). Disconnect the electrical connectors (if any).
How to remove front and rear bumper Jaguar XJ (X350/X358)
How to remove front and rear bumper Jaguar XJ (X351)