What's the best way I can restore my iPhone to factory settings, install iOS 4.3.3 while keeping my baseband at 05.12.01 so it can still be unlocked? I have a 3GS, iOS 3.1.3 with baseband 05.12.01. I don't have an SHSH for 3.1.3, only 4.0 and above. If I restore with stock firmware 3.1.3, will the baseband be upgraded? Because of current battery issues with iOS 5, my goal is to upgrade to iOS 4.3.3 for now. I need factory settings because my phone is getting corrupt from so many apps.