Nickel Plated Headers?

For the most part, they will retain the chrome look, but will 'tarnish' at the point where the hot exhaust gases exit from the head creating a bronze burnt appearance. As far as flaking or rusting, everything does eventually...depending on whether they are triple plated or not.
 
Looks good! I have BBK nickel plated headers and they have not rusted in the two years I have ran them. They are not shiney and new looking, but the plating is still intact. My next set will be 1 3/4" long tube headers w/Jet Hot Coating.