Hi. Can someone guide me on how to upgrade my 3gs from 4.0 to 4.21. My 4.0 is already unlocked, and i don't have the official sim, so i need it unlocked. I know that i have the 05.13.04 baseband, so i need to preserve it. And i have the SHSH for the 4.21 saved. So what is it exactly that i have to do? Get snowbreeze and follow the steps and thats it? upgraded, jailbroken and unlocked??? or is there something else that needs to be done1? thanks for any help