You shouldn't run open headers because cold air can get in and warp the valves. LOL... this one is about as false as they come. There is NO WAY ambient temperature air is going to blow into and go through the collectors and all the way up the hot steel pipes and into the head where the exhaust valve is and be cool enough to do anything what so ever to the valves. This doesn't even get into the fact that for air to blow into and up inside a set of headers, it has to be able to flow through the other side to carry that current of air up to the valves. In other words, how is air going to flow up into where the valves are if it can't freely flow past the valve, into the cylinder, up and out the intake valve, up through the intake manifold and past the throttle plates? It can't, period. I have never even seen, or heard of, this happening with dragsters running short "zoomie" type headers. It's just false all the way around.