TEIN products are developed, tested and produced exclusively for the region in which they are sold. Not every region has different specifications but North America does.
Not every model (BASIC, SS, Super Drift, Super Racing, etc…) has a region specific setup. Product models like Comfort Sport or Super Racing serve niche markets and are therefore universal for the world. A competition car using semi-slicks is similar in the US and in Japan., therefore the same product is sold.
Both Cyber EVO and Evasive use Super Racing coilovers.
HOWEVER, models such as BASIC, SS, SS-P, FLEX and Mono FLEX which are more for street use are made specifically for TEIN USA (North America). Meaning a Mono Flex coilover for a 2008+ Subaru STI sold in the US is different than the kit sold in Japan. Features, materials, basic design, assembly, etc… are all the same but mainly spring rate, valving, and ride height range are different.
TEIN USA Kit: GSS84-FUSS1
Spring Rates Ft: 10kg, Rr: 8kg
Recommended Ride Height Ft: -1.4″, Rr: -1.2″
TEIN Japan Kit:GSS78-F1SS1
Spring Rates Ft: 7kg, Rr: 5kg
Recommended Ride Height Ft: -0.8″, Rr: -0.6″
The specific differences may include spring rate/length, damping force, piston stroke, shell case length and brackets for brake lines, ABS, etc… Products are setup differently because the cars are NOT the same and more importantly the customers are not the same. Admittedly US consumers follow most trends from Japan especially when it comes to performance. However in Japan, the majority of consumers want more compliant suspension systems (softer setups) and do not want the car to be too low. Additional, vehicle ride height laws differ from country to country and in the US state to state.
You can see the difference in ride height between the US Civic Si with JDM body work and real JDM Civic Type R.
In general, TEIN USA setup products with stiffer spring rates and more drop in comparison to TEIN Japan. This is true for both coilovers and lowering springs. For TEIN USA our coilovers setup has changed over the years to keep in tune with the ever changing consumer demand. Our more recent kits have become a little softer than the products which were developed 6-7 years ago but that information is for another blog entry.
On a side note – if any US or Canadian customer wants a TEIN Japan spec. kit we can special order those upon request.