I got into UCI’s School of Physical Sciences, but I want to switch to the College of Engineering. I know that it will be a very difficult process (I have read UCI’s website for information about it). Do you know anyone who has done this and their experience in doing so?
Also, would I be able to take classes the summer before freshman year starts?
Thank you! 
Yes, you would be able to take classes this summer. In fact, I strongly encourage doing so. You can get the UCI student price for classes, but I believe you will pay the non-student prices for now, and then you are refunded the difference later. I recommend talking to UCI Summer to get more exact information.
@UCIAnteaters Thanks! Do you know anything about how difficult it is to switch to a restricted major?
@WiseSeaweed Of course! Essentially what it’ll mean is that you need to be more competitive for when you apply for a change of major (after pre-reqs are completed), as there is a limited number of spots. Your GPA will factor heavily into the decision.