Spring rate is very important...if the rear spring rate is too stiff, the car won't rotate properly. No shock will soften up enough. If the front end is dead, the car won't work as well as it can. If the bars have been in the car for a long time, they may need to be replaced. Both ends have to work together. Pinion angle is another variable that is in play. So, in your example as in most, there doesn't seem to be one answer...we have to plan the work and work the plan, one step at the time.