1. Pull the rear scuff plate upward, then disengage clips A, pin B, and hooks C from the body, and remove the rear scuff plate.

2. Install in the reverse order of removal.
Front scuff plate removal/installation
C-pillar trim removal/installationMazda 6 Service Manual: Manually Shifting Up
You can shift gears up by operating the selector lever or the steering shift
switches (some models).
M1 → M2 → M3 → M4 → M5 → M6
Using selector lever
To shift up to a higher gear, tap the selector lever back (+) once.
Using steering shift switch (some models)
To ...
Mazda 6 Service Manual: Rear door speaker removal/installation
1. Disconnect the negative battery cable.
2. Remove the rear door trim.
3. Remove in the order indicated in the table.
4. Install in the reverse order of removal.
Rear Door Speaker Installation Note
Attach the speaker with the wiring harness placed in the groove of the door
unit panel.
...