Qa1 ball joints just came in. Good replacements?

[INSIDIOUS '86]

Posted this in the suspension forum but nobody seems to know anything about them my next move is to find a circle track forum and ask there maybe. But here is my question

Just got my qa1 ball joints in the mail yesterday. They say race only applications an so far on their site or on summit it says this nowhere or has a single mention of it :/ so that's concern one. It also says on their paper to adjust preload and rebuild every 2000-2600 laps. Are these things made out of dough then?

What does adjustable preload mean and do as well?
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Going to be running this on the street and don't want to have to deal with them less than 50,000 miles from now
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