Have an iPhone 4, iPod touch, or below running iOS 6, and would like to downgrade back to iOS 5.1.1? Doing so is easy is you have your SHSH blobs saved for iOS 5.1.1 and can follow the steps inside. Unlike the beta period of iOS 6, you must have your SHSH blobs for iOS 5.1.1 save for you device now, because Apple has stopped signing iOS 5.1.1.
To downgrade, you will need the latest public version of RedSn0w. We will use the SHSH Stitching feature to combine the appropriate IPSW file for 5.1.1 and your corresponding SHSH blob for the device you wish to downgrade. It may sound a bit confusing, but it's extremely easy if you follow along carefully.
Take a look inside for the full walkthrough and video how-to.