Here's a perfect example of what not to do. Should you opt to cut the factory coil, use a high-powered saw instead of a torch. | 
. Using a torch will overheat the spring, weaken the steel, and make the ride height inconsistent. |
If you want the ultimate control in ride height and adjustability in a matter of seconds, then the coilover conversion is the way to go. While most aftermarket manufacturers have conversion kits for most late-model cars, Global West Suspension Components and QA1 shock absorbers now offer a kit for early A-bodies, Camaros, and Firebirds, along with second- and third-gen Novas. These kits include the upper and lower A-arms, choice of spring rates, and 12-way adjustable QA1 shocks. | |
Spring Selection
In order to have a well-handling car, the entire suspension needs to be properly thought out. This means that dropping the car with heavy-rate springs is not always the answer when it comes to a balanced package of stance, comfort, and corner carving. Having too much spring rate can cause the tires to bounce and lose contact with the road, while a too-soft spring rate can cause the entire suspension to continuously bounce off the bumpstops. So unless you've done this before, it's best to leave the spring selection to the aftermarket manufacturers who can explain in detail how a certain spring rate will react in your vehicle.
Spring rate is based on a combination of the number of active coils, the spring-wire diameter, and the overall spring diameter. A thicker wire diameter, a smaller overall diameter, or fewer active coils will all contribute to increasing the spring rate. | 
If your car seems to sit slightly lower on one side, chances are the coil springs may be suffering from spring sag, which changes the ride height. While you can change springs, another and much cheaper route is to simply insert a set of spring spacers. These mount directly underneath the original spring and are available in various sizes to lift the ride height back to where it needs to be. Do not confuse these spacers with inserts that go between the coils. Those cheaper inserts place undue load on the spring wire and will eventually damage the spring. |
Lowering a leaf-spring car isn't very challenging, but it generally costs more than lowering a coil-spring car. Another option is to find a reputable shop willing to de-arch your springs. Since leaf springs have a 1:1 relationship to ride height, de-arching the spring by an inch will also drop the rear ride height by an inch. | |