From my circle track experiance, once you get all of your joints in smooth bind free connections you will get a car that is much more repeatable on digital scale pads.

So you disconnect your shocks, bounce the car to settle it (front tires on plates), and then check scale readings. Then you recheck or make an adjustment you get the same (very close) numbers or the numbers you should after the appropiate adjustments. If someone overtightens a rear shackle bushings or poly UCA bushing you can get bind easy and chase a race car on scales all night long!