jOJohn, I have the header tank with three facet pumps and four wing tanks. This provides me with a backup pump if the two main wing tanks fail and I have the header tank. Also I can overboard fuel out the fuel vents in the wingtips. many advantages. Header tank with mkII tail, battery mounted on the motor mounts hydraulic pump on back of passenger seat. MT composit prop. CGs are in limits but typically on the aft end. Also the short motor mounts. Send me your address and I can draw you a sketch. I have thought of return system. you can go to a return system to one main tank line before its facet pump and purge witht he other tank. This shifts fuel from one side to the other but how much fuel do you need tp purge for fresh cool fuel. A non event. Also no need to break into your main tanks. A neader is not needed in this instance. Your choice. Are you fuel injected" if not a header is added safety with gravity flow. Bob Smiley