Step 1: Make sure you are running the latest version of iTunes.
Step 2: Download your firmware file here and pwnage tool 4.2 from here (if you use mac) or sn0wbreeze 2.2.1 form here (if you use windows)
Step 3: Create the custom firmware using the file you just downloaded.
Step 4: When the custom firmware is complete, your program will prompt you into DFU mode. After that, open iTunes and press option+restore (if you use mac) or shift+restore (if you use windows) and select the custom firmware you just created.
Step 5: After the restoration has finished, download greenpois0n from here.
Step 6: Follow the on-screen instructions. After the iphone reboots, you will find an app called “Loader” on your springboard. Open it, and install Cydia.
Step 7: After installing Cydia, follow my guide on how to add installous and you’re done!
Step 8: Add http://repo666.ultrasn0w.com/ and download ultrasn0w to unlock your phone to any carrier.
Hey, can i try doing that, and then if my 3G slows down go back and do the steps to the 3.1.3 update.
Thanks again this blog is really awesome!
make sure you use pwnage tool or sn0wbreeze to create your custom firmware, otherwise you will update your baseband and wont be able to come back down to 3.1.3 if things dont go well. Let me know what happens.