On my '98 CSVT, the guy who had the car before me had the WP changed at 42k miles when the impeller exploded ($400 at the dealer). I would HIGHLY recommend changing it BEFORE 60k miles unless you want to chance getting stuck on the highway with an overheated engine, as the impeller could go at anytime. Napa has the part for around $65 (with metal impeller) including gasket, and the procedure is really not that difficult. You can flush your coolant at the same time.
