so i just bought and installed the SLP suspension kit (Bilstein shocks and eibach lowering springs), but after the installation my ride became very firm and rough, like i would feel every bump on the road. my ABS inop sign just came on. i was wondering if something is wrong with the installation. is this kit any good.

 

Might check your third brake light and if it's burned out,that should fix this.The abs and the brakes are on the same wiring diagram.Hope this helps.

 

Depending on the rates of the springs and the type shocks, the ride can be very rough.

I put some aggressive rear shocks on my Z28 and dang if it didn't feel like the axle was bolted straight to the frame. I was "shocked"(pardon the pun) that the ride was so hard from just a shock change. I went back to an "FE2" option style shock. much easier on my backside.

 

Ditto.... Eibach Pro-Kit springs, and the back of the car chopped like a slammed S-10 pickup riding directly on the axle. Nothing I did with the QA1 single-adjustable shocks would help. Ditched the Pro-Kit. Actually rode better with the Eibach Drag Launch springs, but they sit a bit higher than stock.