title_body: Downsides of brewing espresso with high pressure?
upvoted_answer: A higher pressure is fine, as long as it is a controlled variable. You may have to tamp harder or start with a finer grind in order to accommodate the higher pressure. The increase in pressure otherwise would cause a faster brewing time and ergo underextraction of the coffee puck.
  
  What's important is that you keep your pressure consistent. An occasional or erratic bout of high pressure makes your yield unpredictable.