I bought two cans, but it should only take one. Then you'll have extra for touch ups etc. As mentioned in many posts, for the exhaust ports on the heads and the heat exchange cross over in the manifold (if applicable) you only want to do a light dusting, let it tack up and another really light dusting just until you don't quite see the bare metal, then one more light dusting.

That will help it last longer before it discolors from the heat.
In this case less IS more!

Brett!