I can re-check but I think it is both double tubes that are next to each other and just not the outer 2 single ones. I'm not going to take it out on any long runs or probably at all until I figure this all out. I also need to get an inline fuel pressure gauge and see what that is running at.I agree with @Pin_Head , glowing headers, at 3000 rpm with no air flow should not make them glow. Retarded timing would make them glow. Since it's only 2 cylinders glowing I think it's more isolated to a deeper problem concerning those 2 cylinders. Just my opinion. I hope after you change your fuel lines that helps.