I tried it on Project Magna, an '82 Honda VF750C, with some very dulled engine cases. After cleaning the engine and allowing it to dry the S100 is simply sprayed onto any surface that has "lost its gloss and original color." I'm here to report that this stuff works. It leaves behind a bright, black, glossy finish that genuinely surprised me.
Having said that, I have no long-term experience with Engine Brightener. Will it hold up under heat and time? Well, there's 126 customer reviews on the Amazon listing with only 8% at less than a 4-star rating. It sure made the Magna pop.
(click on an image below to enlarge)