The JDM suzuki swift struts are in same size and shape as the PKDM Suzuki Swift's. Only the coil spring used in them is slightly softer due to less thickness as compared to the coil springs used in pkdm. This also make them softer and the car responds better to the bumps and potholes. They are also compressed more due to weight of car and car height from is reduced by almost 1.5 inch. Remember this is all due to this coil spring.
I have recently replaced the struts of my 2013 model swift dlx 114k driven with the JDM ones and below is my experience so far driven 200 km with some rough patches and plenty of potholes. Below is the rating in comparison with the pkdm swift struts.
Response to Potholes: 30% better
Cat eyes: 20% at high speed while almost same at low speed. (I did not dare to cross any "bull size cat eye" at more than 10kmph, analysis based on normal size)
Carpeted road: Same experience
Uneven roads: 5% better
Handling: same
Drive at high speed: seem more mazedar due to less ride height I guess.
Cornering at high speed: Did not try any high speed turn.
Did not hear dashboard rattle after installing these struts which is a treat as dashboard rattle in swift sucks.
Got these struts only for 06k and 0.5k for replacement. These are definitely good value for money. Below is some science to back the above analysis:
One mm increment in thickness of coil will increase the force required to get it compress or extend by roughly 4 Newton (keeping the material of spring construction same). In technical terms, less the spring constant, lesser force is required to compress or extend it.
Strokes law:
F= kx
Where F is force
K is spring constant
X is distance travelled (compression/extension)
It means if the coil/spring is thicker it is more hard and small bumps which exert little force on coils/spring and hence not able to compress it as a result it does not have any dampen impact while a think coil will respond better to this but consider the weight of your car and strength of coils before selection of coils for your car as you don't to compromise the safety of your car. Secondly it is the ratio of weight of car to strength of coil. If the car it is compressing the coil it will quickly go into pothole keeping the tyres on ground and avoiding the free fall as its all about keeping the tyres on ground which makes a comfortable suspension.