I've had white sidepipes on my car since 1970. Mine are alumized. That is molten aluminum sprayed on the pipes. It comes out very white but rough texture. If you sand the coating it turns aluminum color. It has not been hard to keep clean. I just wash them with the same soap that I wash the car with.
Oil spilled on the headers just seems to burn off. The coating prevents rust and if it gets a really bad stain it can just be touched up with VHT. In the 38 years that I have had them on the car I redid them once. That was after someone put their tennis shoe on a hot pipe and it left a shoe print. I could not get that off so I redid the pipes. I should have just painted over the shoe print with VHT. The second coating job was not as good and it has lifted in a couple of areas. I just touch up those areas with VHT.