Just installed AutoRunner Coil Spring Assister yesterday. Suspension has stiffened up and handling has greatly improved. The car is also more composed over speed breakers.
As per the manufacturer;
"Coil Spring Assisters are necessary because most standard car springs are designed for comfort of the passengers and are not strong enough for bad roads and heavy weights carried in the boot, so decreasing the possibility of shock absorber from bottoming and reducing stress on the Bushing.
Coil Spring Assisters doubles the life of your Shock Absorber and Bushing, Increasing Handling and reducing road noise so giving the ability to drive on Indian roads stress free and reducing cost on maintenance."
However for me I found the best part of it is the improved handling. Hyundai cars come with soft suspensions giving you a false sense of comfort. Actually the soft suspension makes the car bounce a lot on rough roads and the body rolls a lot during cornering. This makes you feel sick. Now with AutoRunner fitted (combined with the earlier upgraded footware) the car is really handling well. Not perfect but 10 times better than stock.