I had the brakes done twice on my 96RS while it was under under the 3year/36,000 deal. I have the Y87 performance package, so I have the same brakes as the z28. I only have 45,000, so I haven't had the brakes done since my warrenty expired, but they still pulse. Since you have a z28, I would not use a impact gun as you could damage your aluminum rims and never torque them past 100 ft pounds. That will definitely warp the rotors. The rotors on the 4th gen cars are thin and warp easily. I would replace the warped rotors with a high quality rotor from Baer etc. The pulsing should go away with the new rotors unless you really beat on your car.