Hi Hideaki, you may wanna visit a car workshop to seek recommendations from the professionals there. Here are some workshops which our Motorist Team recommend https://www.motorist.sg/article/676/five-recommended-workshops-in-singapore-by-region

Do check out this articles on coilover and car suspensions: https://www.motorist.sg/article/634/a-beginner-s-guide-to-car-suspension