Need Help upgrading from 3.1.3 to newer OS without ruining Unlock
hey guys im pretty familiar with modding everything from wii's to iphones to playstations but cant seem to find the answer im looking for out there one my normal circuits. i have an iphone 3gs 3.1.3 on 05.12.01 and need to upgrade the OS to something newer as i am unable to access newer apps from the app store. I would like to upgrade my OS to something at least 4.0 untethered jailbreak and still keep my unlock. does anyone know what i should use to do this? thanks for your help in advance i really appreciate it.