Don't settle for generic springs. The noname jobs will quickly begin to sag and take a set, whereas the Hypercoil springs used by LG will not. Hypercoils use topquality wire that is pre-stressed and Blanchard-ground. This ensures that their installed height won't change.
"So the spring and shock must work together. If you just change the shock rate with a knob, without changing the springs to match the shock change, then you have just taken your shock/ spring package out of harmony, and it will not work as designed."
Another critical consideration in coilover design is shock-body length. If the shock is too long, it will bottom out when it's loaded in a corner. LG spent the time and money to have Bilstein build a custom-length body, so there's no chance of the shock bottoming under compression. "When the shock bottoms, the effective spring rate goes to infinity," says Gigliotti. "This leaves the tire as the only shock absorber in the suspension. Obviously, this is not a good thing."
GM Performance Parts has the perfect companion components for the LG coilovers: a pair of T1 sway bars. Originally developed for SCCA Touring 1 racing, these mammoth bars dramatically improve the handling of the C5 and C6 by all but eliminating body roll. GMPP says the bars have been developed and tested both on racetracks and at GM's proving grounds, and that they offer engineering expertise, validation, and durability that only GM can provide.
Coilovers allow wide latitude in selecting ride height. Prior to installation, take a few moments to measure all four corners and note the existing measurements.
The combination of the LG Motorsports coilovers and the GMPP T1 sway bars improved D6C's handling to that of a purpose-built race car, without the abusive ride. Because autocross events are typically run in parking lots, the cars need to be able to contend with bumps and other surface imperfections not usually found on racetracks. With this in mind, LG spec'd a slightly softer spring than usual, giving the car more grip on less than billiard-table-smooth surfaces. It also makes D6C supremely comfortable around town and on the freeway. And the addition of LG's sway bar end links cured one of the big knocks against the T1 bars, which is noise.
While the installation of sophisticated suspension components such as these may seem daunting, the truth is that it's really quite simple. In this issue, I'll show you the basic steps required to install the parts. In an upcoming installment, we'll circle back and give you a look at the actual setup.
Installation of the LG coilovers and GM Performance Parts T1 sway bars is much less daunting than you might think. Once you have the car in the air, remove the wheels, then unbolt the rear upper shock mount. | 
Also remove the lower shock-mount hardware. Repeat on the opposite side of the car. This will allow both sides of the suspension to droop, minimizing tension on the spring. | 
The shock can be difficult to remove at this point, so just pull it loose from its mounts and let it sit. |
With the tension relieved, you can now unbolt the leaf spring mounts. | 
Removing the sway bar end links will allow a bit more droop and room to work. | 
Now you can remove the spring. It's good to have a smirk on your face during this step. At this point, removing the shock should be simple. |