Holy crap!!!

I just noticed that the exhaust manifolds on my 1969 L-78 Camaro have started to show some lite surface rust. I used Eastwood hi temp cast grey exhaust paint after sandblasting them a few months back.
Is powdercoating recommended? I was told it may take the original cast "grain" look away and thus be looked down on at shows. Any other recommendations to combat rusty manifolds?? Thanks.
Darrell
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1969 RS/SS L-78 Camaro