The intake manifold should stay painted if some type of "high heat" enamel is used on it. Exhausts- - - -about the only thing I've seen that stays put well is "stove polish", the black greasy stuff that old-time wood stoves got treated with periodically to retard rusting. It's basically carbon black powder suspended in a beeswax/grease carrier that burns away, leaving the black pigment behind.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!