Clean it with brake or carb cleaner first.
Sand the chrome on the exhaust with some 220 paper until there is NO SHINE, if you are apinting the exhaust.
I used Krylon with no primer and it worked great.
The exhaust will only burn off from the flange to about 6" down the pipe if you decide to paint the exhaust.

Let it dry for 24 hours and you shouldn't have any problems with fuel or oil removing the finish- in fact, my gas cap always leaked and the worst that happened was a stain would start on the tank, but could be wiped off.

The paint stayed.

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If it ain't broke, and you mess with it long enough, it will be.