Funnily enough, I do know quite a lot about rebuilding engines. I also know how much the average price of a water pump is (approx £25-35) so unless you are completely ripping someone off by hiking up the price of a water pump, I have yet to come across a customer who would jeopardise the smooth running of their engine for the sake of an extra £30 odd pounds. But then again I don't know what your mark up is on water pumps, quite frankly, we would rather sell the ancilaries at cost if it ensured that the engine was going to run sweet.