The water isn't under much pressure at all - it just trickles out - probably hits the surface 6 - 8 inches behind the transom.
As I said above I m not sure where or when the mod was done, it was on the boat before I started work there. Its on a Delta so maybe its something they do? Or possibly as the boat was built for us the company specified it?
There doesn't seem to be anything in the Mercruiser manual about it.