I just changed my belt 3 weeks ago and the car is running sweet. Since the tentioner is pricey i just cleaned and greased my old one (there was nothing wrong with it). With regards to the water pump, if it is working fine then leave it that way, don't go changing parts that don't need to be changed. One of the things you should remember about k10's is that they don't like to be messed around with. If you plan to do the job yourself then make sure you have an impact/air gun to get the pulley off, the rest is easy except the bracket for then engine mount the bolts are a pig to get to.