Exhaust manifolds

[heavy71chevy]

My 71 Chevelle with a stock 350 has the factory exhaust manifolds (as far as I know). They look pretty nasty so I was going to take them off and have them sandblasted and ceramic coated. I am also considering putting on headers instead but that seems like more work and I don't know if it's worth the pain and money. Do the factory exhaust manifolds flow decent enough for a stock small block? The car already sounds good with the exhaust that's on it; just wondering if putting on headers is worth it.

Thanks.