When evaluating the HKS GT coilovers at the factory stock baseline, we immediately noticed that the ride was smoother. We felt that it was actually smoother than the factory comfort setting, however we felt that this was underdamped and not the sort of ride quality that we favored, even for daily driving.
In hard driving the car wallowed in the corners with a rapid oscillation that is a characteristic of insufficient damping. There was a slight tendency to blow through the travel and bottom out as well. The GT dampers also exhibited a light increase of low to mid speed understeer. This was not like how were were immediately pleased with the HKS baseline settings on the ST dampers. However please note that the design intent of the GT dampers is a smooth reasonable street ride first and handling second. Out of the box, we would have to say that we preferred the stock dampers better on the cars default middle damping setting.
From HKS the dampers are set at level 15 which is supposed to be the design intent baseline. We spent a few hours playing with the adjustment to come up with a reasonable compromise. The roads around MotoIQ HQ are quite rough with broken pavement and we were shooting for decent handling with a tolerable ride around our neck of the woods as well as decent high speed control over large undulations as found on some parts of the freeway near our HQ.
The HKS GT coilovers are single adjustable with one knob that controls mostly rebound damping with some influence on the compression damping. We ended up with the fronts set at 24 clicks out of 30 and the rears set at 22 out of 30 clicks stiffer. This gave a firm ride that was slightly stiffer than the factory default medium setting but softer than R mode which we feel is sometimes too stiff for the track!
We felt that the GT dampers work as design intended, giving a decent daily driver ride with some potential for improved performance. If you are into track days, drive really hard and run larger grippier than stock tires, you are better off with the the more aggressive ST dampers as you will probably run out of adjustment with the GT's.
If you want to lower your car and want a smooth ride with the ability to turn it up occasionally the GT's might be your ticket. Either way either damper set is a high quality awesome set of coilovers to fit your driving needs.