Exhaust Manifold Paint
I ran across a POR (as in POR-15) product many years ago and used it ever since. Factory Gray Manifold paint. Comes in a little can and you put it on with a brush. When you run the engine the paint melts into the manifold and all brush strokes disappear. The best part comes when the manifold needs touch up. Instead of removing the manifolds to redo them or spending silly amounts of time masking everything off, you just get out your can and brush and touch up what needs it. Crank the engine up and it melts into the old paint seamlessly. Been using this on my Darts now for at least 20 years and it is the ticket, if you always want them to look good.