i would not cut it
inside the muffler on the valved side, there is a Y pip, one end is resonated pipe that goes to the tip, and one end goes to the middle pipe you have circled, and into the passenger side miffler.
when the valve is closed, the exhaust gas goes through the Y pipe into the passenger side.
If you were to do this, when the valve is closed, it would choke the drivers side of the engine, as the H pipe in the middle prob isnt enough airflow.
of course, if you do the golf tee mod.......the choking issue is not there.