That is one area that gets the piss cut out of it. :bigsmile: :bigsmile: :bigsmile:
Ideally that area should be a straight shot cut out to 98% of the valve seat diameter. That area is also called the restrictors.
I built a vortec 350 easily to a solid 400hp on the street using mostly stock components. I cut those heads to flow 98% of valve diam and that thing was a beast :bigsmile: :bigsmile: Of course that is not all of the mods the engine got but the head flow was perfect :bigsmile: :bigsmile: :bigsmile: :bigsmile:
You should be extremely careful if you are going to cut that area yourself. One little slip and the vavle seat is toast.
Yep, 5.0L Ford heads have similar bumps on the exhaust side. I've been told they help with emissions, and they are the biggest restriction in the heads. They are the first thing guys grind out when they port 5.0 heads...