Hi, I recently bought a late 2013 27" iMac. I upgraded the HDD, I got the 1TB Fusion Drive from Apple. I thought the 256GB SSD was going to be too small, and the price of the 512GB one was too much at the time (+500 extra compared to the FD). Now I've started to think wether I should have waited a little longer to get the 512GB SSD or not. I want to buy a compatible SSD and have it installed to my iMac. What are my options? Is it possible to do without voiding warranty? Can I buy the exact same SSD that Apple uses and have it installed? Where can I buy it? Big thank you for help!