For what it's worth, I bought my 03 P5 in 07 with somewhere around 85k miles on it. I have no indication that either the timing belt or clutch or water pump were changed before then, and I have not done any of those since I got the car. I'm currently almost at 220k.
So either my timing belt and clutch were changed before I got it, and they now have 135k on them, or they were never changed, and they have almost 220k on them.
Needless to say, I've been driving on eggshells and prayers for a while now. (boom01)