A competition one is just painted to prevent rusting while on the shelf, as the appearance doesn't matter for racing use.
Show car ones are treated with a High Performance Coating (HPC) like Richard's 1975 Avenger has.
There's no paint that will withstand exhaust manifold temperatures as they can get red hot!
Even chrome plating can't handle it, which is why motorbike exhaust pipes are double walled.
The inner wall takes most of the heat with the chrome plated outer wall running much cooler.
You can always tell cheapy single wall replacement pipes because the chrome goes blue from the heat.