I know this thread is largely about street engines, but I spoke with 3 different very experienced engine builders about this and none of them recommended it. Each of them stated their reason against a gapless 2nd ring would cause the top ring to flutter. What the tell signs of that are, I don't know.
However; when I bought a set of diamond pistons, the rings they recommended were the total seal with gapless 2nd. So I bought and installed them in my pulling engine to no ill effect that I'm aware of, it had practically no blow by at north of 1000hp and sustained 4k+ rpm. The thin ring still had good tension at the end of the year. The pistons didn't hold up as well as the rings. I don't think I would do either one in a street engine that I didn't want to maintenance regularly, as in tear down. My opinion
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