Performance is excellent. Toyota uses Bilstein for Rallying on its award winning Corolla and Celica WRC.
Handling wise is superb but comfort wise.... no idea as it might be too stiff for a small sedan. Bilstein and Koni absorbers are built to last long and even last longer than your car. No Jap absorber manufacturer ever said their product last longer than car.
Their absorber are better than those aftermaker modified spring + absorber.
Koni are Europe made or South Africa and Bilstein are mostly german made.
It wont easily fits onto any Jap car model and only certain model are available.... mostly those higher spec model or those available on EU or America market,
else i would have long fitted onto my car...

Lexus uses Koni absorber....
Mercedes uses Bilstein...