iH8sn0w has released iFaith v1.4.2 with some bug fixes, the tool dump to Save SHSH Blobs in a file for iOS 5.1 on computer, and later on used to create custom stitched firmware that helps to downgrade to iOS 5.01, 5.0, 4.x.x.
iFaith is a Windows only tool and you can grab its latest release through link below.
See also:
Download iOS 5.1
How to Save SHSH Blobs
How to Downgrade iOS 5.1 to iOS 5.0.1, 5.0
Download iFaith v1.4.2 for Windows
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