Production of the classic Mini Cooper ceased in 2000. All Minis produced after that date were made by BMW. Under BMW, the Mini Cooper was transformed into a larger, higher specification vehicle than the classic. Modern Mini Coopers are fitted with Harman Kardon audio systems as standard equipment. This system incorporates a Harman Kardon DSP amplifier, door-mounted speakers and a Harman Kardon control panel. Changing the amplifier in a Mini Cooper involves partially dismantling the interior of the car.
Make a note of the new amplifier's specifications. Amplifiers fitted to current models of the Mini Cooper are 480-watt class D digital signal processing amplifiers. They weigh 1.3kg and are located on a bracket that holds them inside the passenger side quarter panel. If the replacement amplifier is heavier than the Harman Kardon amplifier, you'll need to get a stronger bracket.
Turn off the ignition. It's essential that no electrical work is done on any car while the ignition is engaged. The amplifier is wired to the car battery and draws sufficient current to be lethal if not carefully handled.
Unscrew the plastic rear-trim panel on the passenger side with a Phillips head screwdriver. This allows partial access to the Harman Kardon amplifier and its wiring. Put the screws in a container so that they don't roll away or get lost.
Unscrew the moulded plastic panel on the passenger side rear trim. Use a hex key to detach the plastic moulding that surrounds the rear trim panel. This allows unrestricted access to the amplifier, wiring and bracket assembly.
Disconnect the power wire (red), remote wire (yellow) and ground wire (black). These wires are bundled together with a plastic cable tie. Use a pair of scissors to remove the cable tie, then unplug the power wire. The cables are attached via a 5mm jack. For safety reasons, always disconnect the power wire first. Then unplug the remaining yellow and black wires. Tape these wires to the inside of the quarter panel so that they aren't in the way.
Unscrew the bracket screws fixing the amplifier to the bracket with a Phillips head screwdriver. Unless you need to replace the entire bracket assembly to accommodate a larger or heavier amplifier, it is unnecessary to remove the entire bracket.
Remove the amplifier. Slide the amplifier vertically out of the bracket and set it down in a safe place.
Load the new amplifier. Slot it into the bracket and fit the chassis screw through the bracket tab on the amp. Plug in the ground wire, remote wire and power cable.
Attach the trim panel screws, in order, to a piece of electrical tape. Replacing them is easier if the screws go back in the original holes.
This modification may invalidate any warranty you have on the audio equipment.