This thing is the ultimate mini power machine lol. I have the dual core i7. The SSD is a OCZ Vertex 4, and the 16gb of ram is Corsair. Write speed is 300 mbs and read is 500+ mbs. Applications just flash into open state, and I've never felt a more responsive machine. I use this as my main Xcode dev machine and I'm greatly pleased, I'd recommend this upgrade to anyone. Total cost for the upgrade was $304.74...well worth it. Also have a retina Macbook Pro coming in the mail.