After a 150 something thousand miles, it was time to rework the Supra shocks and springs.  I wanted to lower the stance of the car some.  I also wanted to give myself a little more stiffness under hard turns without sacrificing everyday drivability.  I decided to go with Eibach Pro progressive rates.  The Eibachs are supposed to lower the car about 1.5 inches and the progressive rate will allow the springs to stay fairly soft under subdued driving and to stiffen under hard driving. 
 

In replacing the springs, I had to remove each shock as well.  With the shock out, putting in new springs doesn't require a lot of steps.  Compress the stock spring, remove the top plate, compress the new spring, install the top plate, and release the spring.  The spring has a particular spot it must sit on on the shock, but since the seat is shaped getting the location right isn't hard.  Also, I installed the progressive rate springs with the tighter coils at the top, but it shouldn't matter which way they go in.

1- Having to remove the shocks and all the trouble they entail make this somewhat difficult.  Especially with TEMS.
2- Compressing and loosening the stock spring and then doing the same for the Eibach ones is time consuming.  It goes a whole lot quicker with an air ratchet.

None.

I have enjoyed the new ride of my Supra after this mod.  It may have even saved my life as I had to quickly avoid a ladder that fell off a truck in rush hour traffic while going over a bridge a few days after the upgrade.  With the old sloppy suspension, I may have lost control and who knows what would have happened.  The new springs did lower the ride height about 1.5 inches as advertised.  Final result: as the stock parts needed to be replaced anyway, this was a very good mod for me.  I would recommend it even if the stock suspension is OK if you have the money.