Downgrade 5.1 to 5.0.1 / 4.x without SHSH - 100% Working

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  Download Files:   CLICK

Unlock any baseband  iPhone 3GS, 4, 4S
  Download iUnlocker:   CLICK

Step 1: You have to go to C:\Windows\System32\drivers\etc , and replace "HOST" file with the downloaded one in "Restore Files" folder

Step 2: Open redsn0w and jailbreak your device, you can follow this tutorial - Click Here - but you have to point to iOS 5.0.1 instead of 4.x.

Step 3: Then the iPhone will stop on the recovery mode.

Step 4: Open Tinyumbrella (can be found in "Restore Files" folder above), then click on your iPhone name at the left then press on Start Tss Server.

Step 5: Open iTunes and restore your iPhone with iOS 4.3.3 firmware (Shift + Restore) then close it.

Step 6: You will find error 1013, at this time you have to use Fixrecovery (can be found in "Restore Files" folder above).

Step 7: Open iFaith (can be found in "Restore Files" folder above) and Save shsh file.

Step 8: Open sn0wbreeze (can be found in "Restore Files" folder above) to create custom iOS 4.3.3 firmware and restore with it. Done.

Note: We have not had a chance to verify this guide, so if you gonna try it, please feed us back, specially iPad 2,3 users.

Common Errors: 

• If you get  3194, 1600, 1602, 1013, 1015, 20 errors, you can fix it - Click Here.
• If you get 1611 error, you can fix it - Click Here.