Mazda 6 Service Manual: No.20 noise occurs at idle when vehicle is stopped in all positions/ranges

No.19 excessive shift shock on torque converter clutch (tcc)

No.21 noise occurs at idle when vehicle is stopped in d, s, l ranges, or in r position

Other materials:

Mazda 6 Service Manual: Drive Selection (Some models)
Drive selection is a system to switch the vehicle's drive mode. When the sport mode is selected, vehicle's response against accelerator operation is enhanced. This provides additional quick acceleration which may be needed to safely make maneuvers such as lane changes, merging onto freeways, o ...

Mazda 6 Service Manual: Sst
Some Ford SST or equivalent are used as SSTs necessary for engine repair. Note that these SSTs are marked with Ford SST numbers. Note that a Ford SST number is written together with a corresponding Mazda SST number as shown below. Example (section ST) Example (except section ST) ...