weems84 wrote:Also the coilovers change the shocks out as well. The spring rate is higher on these compared to stock and the lowering springs. I should get a bit rougher ride but alot better handling.
Handling over stock should be improved but not necessarily. And the ride doesn't have to be rougher.
Although I doubt this is an issue with Tanabe, certain manufactures do not test their spring combinations on the target car. And differences between front and rear could be too drastic resulting in unpredictable handling. Others manufacturers will provide shorter springs with the same rates resulting in less travel and bottoming out.
Ride of the car is affected by more than just the springs but the aftermarket does have the luxury of doing things a little differently because they're not producing 100,000+. Progress Auto does a progressive spring winding by varying the spring diameter such that the spring rate increases significantly while the spring is compressed. This could result in a better ride than stock (it does on the Mini whose stock springs are linear) and better performance when pushed hard.
Lastly, shock dampening and stroke need to matched to the spring characteristics. An aftermarkeret spring that's stiffer and shorter than stock could overpower a stock shock and take it out of it's normal performance range. This is typically exhibited by excessive bouncing, or overshoot going over a bump. (Note the job of a shock is to return the vehicle to it's steady state position. Overshoot is when the energy absorbed and returned by the spring causes the vehicle to move to a position beyond or above the steady state position.)
Bottom line: When buying springs, consider replacing the shocks and struts as a set. When replacing the suspension, consider how the car will be used and whether the combination meets your needs. Lastly, know what you buying is going to behave as you expect.