I admit I am new to this iphone business, as my friend just gave me an iPhone 3g two weeks ago. However, I feel that it runs quite slowly. According to the forum, this is because it is running 4.2.1. 1. Will I benefit from a significant speed increase if I downgrade it to 3.1.3? I have read that even if I change it back to 3.1.3 there are things left behind from 4.2.1 that will still slow down the system. 2. What is your opinion on using Whited00r? It's supposed to be 3.1.3 hacked to allow 4.2.1 features, but I haven't been able to find a lot of info about it. 3. None of this affects my ability to use my iPhone with T-mobile right? I can change the firmware to 3.1.3 and be ready to go on T-mobile? In order to run it on my provider (T-mobile), I jailed broke it with redsn0w, installed 06.15 baseband and unlocked it with ultrasn0w. I also tried the reboot trick to improve performance to no avail. I found this guide on changing it to 3.1.3, I assume this is how you do it: http://lifehacker.com/#!5572003/how-to-downgrade-your-iphone-3g-from-ios-4-to-ios-313 If you have any suggestions please let me know. Thanks!