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I recently purchased a 2014 Macbook Pro Retina 13". Can I buy one of those OWC SSD and replace the SSD? I have a 128 GB SSD on my current laptop. Any help would be appreciated.
Sadly, there are no third party suppliers yet for this system. You will need to wait to see what OWC or Transcend offer for your 2014 model.
You can use one of these SSD: Transcend JetDrive 720 (Mac Book Pro 10.2) Transcend JetDrive 725 (Mac Book Pro 10.1) They might be 240/480/960 Gb capacity.