[jpnovak]

Agree with everything said so far. There are a few missing thoughts to the process.

IMO the biggest advantage of coil overs is the ability to use progressive wound springs. However, most suppliers ship linear rate springs. You could be missing the gains related to ride quality AND lateral load handling.

The second is damping. if you are not changing the damping of your shocks when you add stiffer coil over springs then you have harmonics that are not matched. Stiffer springs require reduced compression (jounce) damping and increased rebound damping. Think of it. It takes more force to compress a stiffer spring. If you add additional damping force on top the ride can be harsh and jittery because of limited travel. Then the spring can be bouncy on return because it wants to return back to its original state faster than the damper can keep up. Ever watch a lowered car bounce down the road? Not good for handling and not confidence inspiring behind the wheel. Make sure your suspension system is well matched and properly balanced to the car and its weights. This is all true whether coil over or torsion bars.