Seeing as how I will be installing H&R lowering springs on my 97 x3 in the springtime, I have been researching what type of struts/dampers to put on to replace the stock dampers.

The KYB GR2 is the one I have been eyeing as it is reasonably priced and is said to be a decent entry-level performance damper. To find out how it compares to the stock dampers, I e-mailed KYB to see if I could find out the damping rates of the GR2s for my car (as I said, it's a 97 x3 Accent).

As far as damper rates go, there are two measurements that have to be taken into account: compression/bump and expansion/rebound. The "rate" of a damper refers to it's ability to control the springs oscillations... in other words, to keep the wheels planted on the road surface, and to prevent that floating feeling when driving over wavy road surfaces. We all know that without the proper dampers, any car with any springs will bounce and result in poor control at speed. The rates of any damper will change as road conditions change. In a sense, dampers react to the road surface and provide the necessary level of control, up to the damper's limits of course. Rates are measured in Newtons (N) or kilograms (kg) of force. They are also measured based on speed. In this case, meters per second (m/s). Anyone who has taken high-school physics will recognize these terms.

Thanks to Troy Horn at KYB and the Hyundai Webtech website (www.hmaservice.com/webtech) I'll compare the damping rates of the GR2s for my car with the stock dampers from a 2000 LC Accent (as Webtech doesn't have damper specs for the x3, just those for the LC) and a basic 2003 Tiburon 4 cyl with the normal, non-sport suspension. The distinction between the normal and sport suspension on the '03 Tib is important, as the dampers included with the sport suspension have MUCH higher damping rates and are way out of the Accent's league.
So here goes: (all rates in kg at 0.3 m/s)

KYB GR2:

Front: 140 kg expansion/30 kg compression
Rear: 90 kg expansion/30 kg compression

2000 LC Accent (stock struts):

Front: 55 +- 7 kg expansion/24 +- 5 kg compression
Rear: 41 +- 7 kg expansion/18 +- 5 compression

2003 GK Tiburon 4 cyl (stock non-sport pkg struts):

Front: 105 +- 16 kg expansion/33 +- 7 kg compression
Rear: 65 +- 10 kg expansion/23 +- 6 kg compression

Just as a note, the dampers included with '03 Tiburon sport suspension package feature damping rates almost twice those of the non-sport dampers. To put that in perspective, in SCC's article about the best sport compact car for under $20,000, they stated that the V6 Tiburon with the sport suspension is probably the only car they felt could take lowering springs without a damper upgrade.

As you can see, the GR2s for the x3 are actually stronger in some aspects than the stock non-sport '03 Tiburon dampers.

And the GR2s are MUCH stronger in both expansion and compression than the stock LC dampers. As for the comparison with the LC instead of the x3, Webtech doesn't have listings for damper rates for the x3, so I used the LC instead, as it is not too much different in weight and has a similar suspension setup.

Sorry for this long-winded post, but I thought I would share this, as there has been some talk about the GR2s and whether they are suitable for use with lowering springs. I would have to say, that at least for the Accent, they are.

For coilovers sleeves and the higher spring rates they usually feature, I would go with a better damper than the GR2, maybe Koni adjustables, but for standard lowering springs, the GR2 should be able to keep the ride under control, quite nicely.

As a note, the GR2s for the Tiburon, the 1st and 2nd gen models, for example, should also be stiffer than the stock dampers, so it would likely be a good upgrade for the Tib as well.

I hope this helps someone, anyone, in their search for aftermarket/performance suspension upgrades.