I dont think the plastidip would last long, the heat and gas blowby would take a toll on it quickly, at least I would think it would.
Do it! What is the worst that can happen? I used BBQ gloss black on my tips with not very high expectations, but two years later, still looking good!
200? I would not have guessed that. Think I paint mine though, too hard to hold the car up to dip it.
Tips get a lot hotter than 200°, it would probably start the Plasti-dip on fire. It is rubber after all. And they do make Plasti-dip paint in a rattle can.