Notcom is the developer of the program TinyUmbrella and he is definitely one of the experts in the restore method using SHSHs saved in Cydia. Yesterday I presented you with a possible downgrade method for the iPhone 3GS from iOS 4.0.2 to 4.0.1 without using an SHSH saved in Cydia or on the computer, the method that I categorized as false because after a test, I failed to restore using it. Last night Notcom confirmed the same thing through his Twitter account, so there is no point in relying on that method because it is 100% fake, and the person who made the tutorial used an SHSH from Cydia for the restore.
No matter what you hear from others, remember that that tutorial is 100% fake! Those who managed to restore using that tutorial either had SHSH saved in Cydia and didn't know, or they didn't manage to do it and are lying.
