TRD Springs GuideThe following is not a guide to the spring install, but rather a guide for people to see how much the TRD springs actually preform, as well as how much they lower the car. You should not attempt to do this install yourself unless you are a mechanic, or have delt with suspension's in the past.
I know that the TRD kit and the Eibach pro kit are supposed to be the same thing, and I have found from personal experience that the TRD drop is stiffer by about 20%.
The following are some pictures to give you an idea of what to expect.
Stock Ride height for the Front of the car, measured from the ground to the fender well lip is approx 26 2/16 inches. (Fig 1)
(Fig 1)
Stock ride height for the rear of the car, measured from the ground to the fender well lip is approx 26 inches. (Fig 2)
(Fig 2)
Here is a picture of what to expect once the springs arrive.
TRD ride height for the front of the car measured from the ground to the fender will lip is approx 25 1/3 inches. (Fig 3)
(Fig 3)
TRD ride height for the rear of the car measured from the ground to the fender well lep is approx 24 2/3 inches. (Fig 4)
(Fig 4)
Source...
http://www.celispeed.com/installs/trd_springs/index.asp