Basically my sisters friend has a base model 13" late 2013 retina Macbook pro. It only has a 128gb hardrive but she would like to upgrade the hardrive to a larger one without paying a fortune to get it done. Ive looked online and there are several guides on how to do it, infact you can even get an enclosure to put the old one in and use as an external. Looks like a very easy job with the right tools. The only issue is that it seems this is not a user servicable machine in any way and she is concerned about the warranty. Now my presumption is that it would only affect the warranty if the warranty claim was too do with the hardrive and that the rest of the machine would still be covered. Is this correct?, ie if the screen or motherboard went bad they would still repair it despite the fact she had replaced the hardrive? Are there any security seals to break to get at the hardrive?, thinking she could just keep the original drive and replace if she did ever use warranty.