These cars have a semi trailing arm rear suspension with terrible geometry, the lower the car is the more camber and toe you gain. Fresh shocks and springs will restore the original ride heights but the oe rates are pretty soft. Many people slot the holes in the crossmember to allow for some level of adjustability but that's pretty limited. The 510 uses esentially the same irs setup and there is a small outfit making adjuters for them
http://www.futofab.com/index.php?option ... &Itemid=22 May or may not work as the bushing size might differ but if you are up to the fab work you could replicate these or modify a set