I'm keen to learn more on this. Hard to tell from the video because the camera was so far away, but just how loud is it? Is it as loud as if you were to start the motor out fo the water when flushing?
I reed that in USA Superlight Tunnel Hull Boats APBA rules they use two exhaust holes in the lower unit to improve performance.
50.127 Exhaust Holes: A 1- 1/32” (one and one-thirty-second of an inch) diameter maximum exhaust relief hole shall be allowed on each side of the
gearcase only. This dimension may be measured in any two directions (Mercury/Mariner 59 ci excluded).
Anyone have experience about better performance by this way?