Today, my trusty mechanic installed the Eibach's springs. He show me the two rear suspension bolts to perform the alignment. He did not touch them to install the rear springs(which does not mean that it do not need to check an alignment). Two hours labor. Previosly, he took car's hight measures and put paint tape on one of the shop walls in order to adjust headlight patterns after the spring install. After a round street trip, he confirm the 0.8" drop height front and rear. But the headlight patterns did not change at all, so none adjustement was required, for now. By the way, the height headlight adjustment is with a cross screwdriver, there is not any nut to do the job in my Stinger GT2 ?????.
IMHO, there was a big suspension performance over speed bumps and taking the highway curves and exits, zero floating behavior, more feel of control.....very happy with this upgrade.....