The flap is closed until 3500rpm. It does open up and leave the left exhaust open on start up and above 3500rpm. So if you put the car on the dyno you won't see anything different above 3500rpm. Unplugging the cable will leave the left exhaust open, more noise, and will also get rid of the rattling sound some of us have an start up. The rattling sound is actually the flap assembly turning to close the valve.
Hope that helps