People Titanium changes color with heat... its done with a torch or electricity. it is just oxidation in simple terms, just like rust what happens when you use metal polish on rust? it goes away well if its just surface rust.

 

I've used the Mother's mag polish & billet polish and it didn't remove any of the color. I just use a little bit by hand with a towel.

 

If you polish away the burnt look, is it possible to torch it again to get it back? I'm picking up a titanium exhaust that has an uneven burn and I'm about to polish it up.