Hey guys, I've tried searching the forum and wanted to ask myself before I bit the bullet and upgraded. As stated in the topic, I have a 3g on 3.1.2, unlocked to work on T-mobile. My baseband is 5.11.07. I have heard mixed reviews about updating your 3g to 4.x so I held off but I am working on a project for my Information Systems class that makes use of the Iphone GPS ... needless to say, I have found that the Iphone 4 gives me more accurate results than the 3g. I am hoping that i can get better gps accuracy on my 3g by updating to 4.x but after looking at some tutorials, there is a chance that my gps can be disabled if I update to 4.2.1. Can anybody offer a solution or maybe a few links that can help me out with my dilemma. I read about making custom IPSW files but am not sure how to do it exactly. Is there anybody on a 3g now that is on 4.2.1 that has there gps working ?