How to Upgrade iMac Hard Drive (2009, 2010, 2011): EveryMac.com
iMac Hard Drive Upgrade to SSD - Your local Apple Repair Specialists
2011 imac 27" 32GB - final stage of 1TB + 2TB SSD upgrade (replaced HDD & optic drive). Also cleaned out the fans and case. Running 'SSD Fan Control' & 'Macs Fan
How-To: Now's the right time to swap your old iMac's hard drive for a fast new SSD - 9to5Mac
OWC SSD Upgrade Kits for 27-Inch iMac 2011
Apple Restricts Hard Drive Replacements on New iMacs - MacRumors