I've gotten better results with brush on vs. spray. Don't get me wrong, I use a lot of "rattle can" paint. Don't spray the insides, it will stink as it burns off.
I have a pair of standard 289 exhaust manifolds in the "to do" pile. One side will be painted with regular Eastwood high temp exhaust brush on paint, the other with Eastwood Stainless high temp brush on paint. I just want to see the difference.
I have used Mckay's Graphite spray in the past, but it doesn't seem to last.
Jim