Extremely good for gas use, perhaps overpriced because other iridium spark plugs, even those from NGK used for Lpg, are 30% cheaper (at least for the 1.8 tsi that I have experience with). They are the only ones that the "petrolheads" do not complain about problems with gas operation.

They are used in a car with LPG, which with regular spark plugs, a short time after their change, it started to have interruptions in acceleration at low RPMs if I pressed the gas pedal deeply. Something that didn't happen when it was running on gasoline. Generally, there was hesitation with the gas.
With regular spark plugs, the problem would go away when they were new, but it gradually appeared as time and mileage passed.
With these ones that have been on for almost a month, the acceleration is smooth without any problem, but I will wait and write again when enough time has passed to see if the huge price difference is justified (four times the cost). If they last four times longer, then I have no reason not to buy them again. For now, four stars, until their durability over time is tested.
Edit: If their price wasn't four times higher but only twice as much, I would say they are worth it. However, they didn't withstand the expected. They definitely lasted much longer, but not enough to justify the fourfold price. If you know how to change them yourself, it's better to stick with regular spark plugs and regular replacements.