The amount of vague information here is pretty surprising. Springs in relations to ride quality and ride height is barely mentioned here, yet so much is blamed on the dampers and price. Yet no one is questioning how the spring comes into play here....
9 times out of 10 what makes or breaks a suspension system is the capacity and quality of the springs and its implementation of supporting the weight of the vehicle. At the end of the day it is the spring"
COILover" that facilitates the working motion of a suspension system. All other items and factors are secondary to this.
Most kits that have bad road feel, improper wheel travel and bump problems comes from a improperly matched spring for the ride height set by the user and overall compression capacity for the weight and and subsequent load during harder driving situations. The damper is not suppose to support the weight of the vehicle, its job is to absorb road imperfections and harmonic imbalances the
SPRING creates. Having shocks with valve rates set stiffer to mitigate spring binding and bump is a poorly formulated solution for bad wheel rates. In most cases the damper should be as free flowing as possible without limiting spring travel.
There is a reason springs are usually the only object in the suspension system that has the [force per travel (ex. KG/mm)] information listed in the details of the product. You'll probably never see the shocks value of measurement because its extremely variable based on several factors.
It was mentioned earlier in this thread, but even though the defining factor of the kit is the spring rate (and overall load rating), the overall cost for a kit is defined by the quality and features available on the shock. Where as springs generally have a fixed price, the design of a shock is dependent on its tune-ability and build quality, most of which are unnecessary additives for road cars once you get passed the basic ability to change ride height and compression and rebound.
Way too much emphasis are put on the design of the shock here and its function. The tube design does play a role in overall cost and implementation, little of its capabilities are a defining feature. On average, a normal road car such as the 370z will only get up to about 5 inches and compression and rebound from static ride height. Any version of monotube or twintube damper can support this wheel travel. But in almost every case, a twintube shock is the cheaper option. This alone is the primary reason behind it being used more in OEM and lower priced shocks. In either case, neither design should have to bare the load of the vehicle and the bending forces of the wheel.
I can elaborate further for those who care. With regards with some problematic information -
This is so vaguely uninformative. For one - If you are going for the "stance" setup, its even MORE important to have the correct setup. With a lower suspension than advised, you are dealing with decreased wheel travel. Secondly - Saying the dampening is WORSE is horribly vague. What defines worse here? Way too stiff? Way too soft?
Well if its too stiff then that would actually make sense, as you have reduced travel and in turn reduced time for absorption. Instability can come from a plethora of factors in this instance. Bottoming out, not enough travel before bumpstops, Improper corner rates, and overloading the tires from any of these reasons.
Saying the dyno figures are off from "coil to coil" doesn't exactly mean anything either. Was the preload values the same? Was the temperatures the same? Was it tested with or without a spring? Saying this gives zero emphasis one what the ACTUAL problem could be. A company simply having horrible consistency between products doesn't truly argue bad quality but incompetency of the technicians of assembling the products.