I just had the Eibachs placed on my 98 GTS. While being done at Finish Line they also adjusted my shocks to a firmer setting. The ride difference is amazing. The car is much more responsive at turn in and the rear end follows much better than before. The car has only been on the street but I couldn't imagine tracking it with the stock setup now that I've had them adjusted..
I also have to mention -- Tom at Finish Line was amazing. He installed the Eibach's, adjusted the shocks (1 1/4 turn at all corners), and re-installed my swaybar -- all in an hour and forty five while I waited... Price $120 -- It's great to have a viper tech who really knows the car, no viper tax here..