Hello, Let me offer you some suggestions. First for the water cooling. Start from the water pick-up then go into the head, out of the head to the header and finally out the hull. Next for fuel. Start with the carb to the fuel tank pick up. Then the tank top vent is hooked to the exhaust for pressure. To fill or empty tank detach or install filler fitting in carb line. For quad exhaust solution. The exhaust could be split into quad however proformance is going to be lost since a tuned pipe is not used. It will most likely drop the rated output to the level of a .60 . Make sure you insulate or isolate the exhaust from the hull to keep the heat away.