Here is the Corsair setup.
The ABS cowl did not stand up well to the vibration over time, and the baffle was not as efficient as it should have been, due to it not being close or tight enough around the motor.
You can see the lip created in front of the eflux hole which was just heated with a heat gun and bent. It did make a difference but I was having other issues with the 120SP and the Corsair now has a Saito 125 in it.
The 120SP was a loverly engine and pulled the heavy Corsair like a freight train. Not fast but with heaps thrust.