Thanks to Notcom, creator of TinyUmbrella, we can now downgrade iPhone 4 and iPad 2 from iOS 5 back to jailbreak friendly iOS 4.3.3 or 4.3.5.

Although an untethered jailbreak for iOS 5.0.1 shouldn’t be to far away, if you are tired of broken apps and having to boot your jailbroken device in tethered mode, you can now roll back to a good older iOS and jailbreak it in untethered mode.

TinyCFW (for both Mac and Windows) can successfully downgrade an iPhone 4 and iPad 2 (GSM) running iOS 5.x to a previous version iOS (4.3.3 or 4.3.5) without getting stuck in an error 1015 recovery loop.

NOTE: this will only works if you have previously saved SHSH via TinyUmbrella.
This method will not work on first generation iPad or iPhone 3GS.
Your computer needs Java and at least 2.5GB RAM.

Download TinyCFW for Mac
Download TinyCFW for Windows

-Rename  tinycfw-0.1.jar to tinycfw.jar. Launch the application by double click on the jar or run the .exe file.

-Click on the top button “Choose Current IPSW“.
-Choose an IPSW for which you have SHSHs for. Here I’ve selected iOS 4.3.3 for iPhone 4.

-TinyCFW will now scan and tell you the firmware and baseband versions in the IPSW you selected and the firmware and baseband versions that will be in the target IPSW when you click the second button.

-Click ‘Save Target IPSW‘ and within a couple of minutes, depending on your computer, a new IPSW will be created with the name:

.bbupdate.ipsw

-Now you can use iTunes and TinyUmbrella to restore your device with the newly created firmware. Hold Option key on your Mac and click Restore on iTunes. Windows user hold the Shift key before clicking Restore.