Tien S are supposed to be a decent upgrade on the OEM springs.
However they are only a 14/17mm drop so IMO not a lowering spring as people keep calling them and recommending for others looking to lower the car.
SO, IMO, if you want to lower the car, buy some lowering springs (Apex, Eibach, K Sport etc) if you just want to improve the handling a bit on top of stock, buy the Teins.