After owning an AT Miata for 4 years I was use to pulling back on the shift knob to up shift and pushing forward to down shift when in manual mode. This is opposite of the controls in our AT 370's. After 5 months I still got things mixed up if I wasn't paying attention when I switched gears so I decided to reverse the leads to make my Z shift the same as my old Miata.
After this mod, the manual shifter will work opposite its original factory setting. The steering wheel paddles continue to work as before.
Skill: Low, mostly removing trim pieces.
Time: Less than an hour.
Tools: Philips screwdriver, flat head screwdriver, safety pin.
To start with remove the trim pieces around the shifter, the knee pads and the center console. Rather than repeat those instructions, see page 2 of this thread
DIY: Rearview Camera & DVD for rarwz's instructions. Note: you do not need to remove the shift knob itself for this mod, also skip the parts of rarwz's instructions dealing with radio removal. Also, I did not loosen my parking break, I was able to remove the center console by pulling the break up as far as it would go.
Once the various trim pieces are out of the way, you need to twist the black plastic piece with the shift positions (P,R,N,D) out of the way. There are 4 plastic clips (Pics 1 and 2) that need to be released, use a small flat head screwdriver to pop them loose. No not disconnect any wires from it, just twist it out of the way to see the large white connector underneath it (Pic 3).
The white connector (M137 in the service manual) is held in place by a clip to the shifter assembly, to pop it loose push it toward the passenger seat. Once it is loose disconnect the two halves by pressing the release tab and pulling. We want to modify the half closest to the drivers seat (the part with the male connectors). Carefully pry the safety clip off of the connector (Pic 4).
We now want to swap the Light Green and Yellow wires (these are pins 2 and 3 in the service manual). To remove the wires take a safety pin and insert it in the large opening below the metal connector and pry up the small plastic clip holding the connector in place. You can then pull the wire and connector out of the plastic housing. See Pic 5 for an idea where it insert the pin, if you lift the clip correctly the wire will pull out easily. Pic 6 shows one of the wires out of the plastic housing.
Note: Pic 6 is just to show a disconnected wire, ignore the wire colors in this pic. When this picture was taken I had mistakenly removed the wrong wire.
Pull out both the Light Green and Yellow wires and swap them. Pic 3 shows the final assembly with the wires in their new positions. Re-assemble everything and you are done. Don't forget to put the white safety clip back on the white connector after switching the wires.