Rick
Like Steve above my 1999 car is equipped with both SSL front end and SSL 5 Link Rear suspension.
I find the ride improvement was more marked with the front end work , the rear end was not as dramatic BUT the handling improvement was really significant with the 5 Link rear.
The car turns in so much sharper into corners , the initial understeer is totally banished and the car behaves neutrally all through the corner (unless you go into hooligan mode and deliberately provoke power-on oversteer) It is worth it for that alone , but ride does improve as well .
If speccing the kit for the rear, then request the "softest" spec dampers , used to be Bilsteins , now Spax adjustables I think, stay away from the Quantums which are too harsh.
AS Steve says the total conversion is not cheap , especially if you are having it fitted by a professional, but in my book it is value for money.