[wfedwar]

Generally no real loss in power until something starts to fail, such as rings, valve seats, cam lobes, whatever. Rings can wear a certain amount before they negatively affect power. I'd say as a general rule, most modern cars with good maintenance that are driven reasonably will go 200-300k miles before power really starts being affected. As mentioned in a previous post, usually engines make a little less power at first due to extra friction and poorer sealing before all the parts get worn in.