My co-worker (sits next to me at work) built a system a month back and installed it on his Expedition. He gained about 20% better milage. He only needs to fininsh the cooling of the water and the system is complete. He has been able to maintain his water at a normal level for over three hours. I think he needs to bore out some whole for better water flow and efficiancy. Im next in line for his install; In the next few weeks or months.