Step 1: Download the latest version of iFaith from

and iOS 5.0.1

Step 2: Build a singed firmware file by clicking on 'Build *signed* IPSW w/Blobs'

Step 3: Browse for the SHSH blobs file that was previously saved to the device in use to downgrade back to the old 5.0.1/5.0 firmware. Now iFaith will ask you to choose the stock firmware of which you want to create the custom firmware file from. Once completed, iFaith will have a new custom firmware file waiting for you on the desktop with SHSH blobs incorporated for the firmware you're downgrading to.

Step 4: Finally, enter DFU mode with iFaith and then use iTunes to restore to this custom firmware file.
This is all that's required.