In my picture... I have it hooked to an 800 engine. On your 720... that top hose feeds the water injection to the rest of the exhaust. DO NOT CHANGE THAT HOSE !!!! The top elbow is a calibrated fitting, and if you divert water from it... you will over heat the exhaust.
OK.... on your ski (assuming it's a 95 XP) You will have a hose on the bottom of the exhaust manifold that heads toward the rear of the hull. Somewhere, there is a T-fitting in it. One side goes to the exhaust outlet, and the other side is the pee-hole. Disconnect the pee-hole hose, and hook the new hose there... and plug the old hose.