Before you go any further, do yourself a favour and buy a power factor pipe for that engine. It is a huge, huge ,huge difference. Keep the exhaust manifold and get a spigot welded on it to accept the powerfactor.
But if you must run this, find the port in the exhaust manifold that when you blow air in it, the air comes out the top of the head. On this manifold you must split the water going in to the manifold because if you dont one exhaust port will run hot.
The port you have circled is like a water injection, you need to put a main makuni jet in it to restrict the amount of water that enters the pipe. I think a 60 is good but adjust it to get the pipe just warm enough to almost sizzle any water sprinkled on the pipe itself. This is important, the pipe will be absolutely horrible if you dont do this properly. So you are going to split the water coming from the pump to the water injection port that you circled, then you are going to split it again so you have water entering both sides of the exhaust manifold. Then from the head outlet ports you can connect it to the outlet port exiting your hull. At this spot you can split it and Tee it to the stinger port. you may want to use a jetworks inline pressure check to regulate how much actually goes to the stinger.
for fun try this,... leave the makuni jet out of the water injection port, but hook the water to it. Try the ski. then put a jet in the fitting. try the ski again. now you can rate this improvement. Now take that and x it by 10 to get an idea what the powerfactor pipe is like on that engine.
Good luck man.
