You paid to have the waterpump replaced? Or the timing belt replaced? Or both?
I replaced my timing belt and water pump myself...just to avoid such problems.
May I suggest the Deyeme Racing Street Waterpump on your next replacement? It'll free up some HP and be able to tollerate those high rpm days. But...the OEM waterpump seems to do okay for most people too. Just gotta do things yourself is what I've learned.