I think that they came out in the late 80's or early 90's
I started hearing of them and SRP around the same time. And at around 200$ cheaper than Wiesco's or JE's etc, they look pretty good for a 'budget' build
When I called the guy selling them on Ebay, he said the tolerence was around .003-4. I've never bothered with short skirts (on pistons that is) but I'd doubt that you would get much noise with that distance. In addition, at a high comp it shouldn't take to long to heat up and quiet things down.
I did pull apart a couple Olds 215's and the pistons had NO scalop skirt shape. Just a round slug all the way down..
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