If you look at AH's engine bay pictures, it sort of like that. I had 2 ground wires from the battery in addition to the stock ground cable. all grounds are connected as a complete loop, grounds to the ECU, the transmission, the front of the engine as seen in AH's pics, etc.

 

btw the only difference you get is smoother idle and shifting, slightly better torque response, no extra power

 

so this is basically a mod that would be more relevant for an AT owner?

 

yes or for anyone with custom audio system, hid conversions, etc.