Not hijacking Beasties post about Alcons warping, but along very similar lines...

I have AP 4 pot upgrade on my MY99 Sti, I have warped discs, but unsure if it's the AP fronts or the standard rears, I have been told that the rears do have a tendancy to warp, which should I change first?! :( any ideas?

Meecho, are those genuine APR discs you've got upfront? If you've warped them, you are a member of a very small and exclusive group of mad brakers :eek: Yes, it is possible to warp the rears, especially if you've got big brakes up front as they keep on going when the rears have past their operating maximum and you then do some damage.

Anyway, it's very easy to check. If it's warped fronts, you'll feel vibration under braking through the steering wheel. It's quite unmistakeable. On the rears it's harder to tell, can feel like a wheel is out of balance, but if you feel vibration through the seat and only under braking, suspect the rears.

Richard.