go search in mudah.my for used adjustable spring up for sale...
6k front,4k rear would do fine for daily..for more stiff then can go for 8k front and 5k rear...for full track time then go for 10k front,6k rear or more depends on your engine weight and power...
if u prefer new spring google for HWL top erfect sungai buloh and u can order any spring hardness for adjustable for rm250/pair (2pcs)