I have a sump system a friend of mine and I designed and welded in the stock tank. We didn't quite get it at the angle it needs to be at so it needs some improvement but it works. I can run it pretty low and not have any trouble. That being said if I go bracket race I fill it all the way up to alleviate any worries about fuel. The only time I have noticed a problem was under heavy braking and low fuel levels, no pressure loss but I could here the pumps rev up some.