It is known that these wireless switches being used to prevent muffler damper from closing causes problems with the wireless functions of the car.

Second is if you read the above closely you notice there is a lot more going to to the EFCM to simply be switching it totally off by turning off the voltage to the controller via these wireless switch functions.

Third as data shows the effects to fuel trims going lean when damper is open at low engine loads and as GM states above the concern for exhaust valve activity.

We suggest a better method that keeps the EFCM fully functional and could be done using a normal on/off switch ( or wireless could be used) by simply cutting the vacuum hose by the firewall as shown below and inserting a electric solenoid that is switched.

This way the EFCM is functional all the time and your simply controlling when there is vacuum to control dampers in mufflers.
We suggest as shown below a solenoid that has a coil that reacts very quickly and with low current draw.