I agree that a plate under a cool undertail is kind of like a turd on top of a New York Strip steak, but IMHO putting the plate on a bracket looks even worse, especially if you bend it to fit a curved bracket. Then the tail looks cool but the swingarm looks like crap. You've just moved the turd, it's still there.
I think tucked up under the tail is where it belongs. If you put it on the swingarm it tells the world that you don't care about performance only looks, and I like to have both with an emphasis on performance.
Oh, too much wind resistance also if you mount it on the side. I know , I know, everyone has an opinion, don't flame me please. To each their own.
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