If you're looking for a great street setup with light track capabilities, Eibach's Pro-Kit is for you! You will realistically see a drop of 0.9" Front, and 1.1" drop at the Rear with the Pro-Kit. Ride quality is firmer than the factory Si springs, but not super stiff for a daily commute.
Our Red Si (pictured) has tested these Springs for well over a year. The SPC Performance Rear Camber Kit is not mandatory, but is available if you'd like more adjustability with your alignment.