I have had mixed experience. I will avoid the KB 280 pistons, as there is too little material between the top ring and the exhaust notch where the piston is at the hottest. I have had failure in an engine taking out the ring lands in the 4 center pistons. Tried to evaluate the issue and compared different KB hypers, and the 280 is unfortunately nothing I would recommend. I also see there are different designs on these within the same part number for the valve notches. The ones that are milled through have this issue. If all conditions are correct, they might survive. If something overheats or detonates, they can fail, and they do much faster than forged pistons. I did follow all installation instructions, but it did not matter much.
No such bad experiences with the KB LA hypers, they are also designed differently and have more metal above the top ring.
But, I have measured the skirts after some run time, and they seem to deflect in the bottom and give more piston slap. Look at them, there is almost no support there.

So, as an engine builder I cannot recommend them, especially as they have been way overpriced lately.
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