My experience with us they started off ok. I bought them for appearance not performance.
They have developed a knock on the front if you hit something hard. Say a pot hole when you don’t see it. And now have a snapped rear spring. These have been fitted for 4-5 years. So maybe that’s there life time up.
ThAt my experience with them and my issues just but they have been fitted fir a good few years.
Mines on a A3 sline
Why are you fitting coilovers?