Have to respond to all you BS posts. So people won't the wrong idea. Again.
Originally Posted by speedy2056
The author: Downgrade iPhone 4, 3GS from iOS 4.0.2 to 4.0.1 Without SHSH Blobs Saved [Guide] | Redmond Pie
First sentence: "Ok guys let me clear this upfront. I havenít tested this method yet, but by the looks of it, there is no reason why it shouldnít work."
Update: "Ok guys, I know I took a little long to provide this update but this was because I was thoroughly testing this method to see if it really works. After trying it out on my iPhone 4, 3GS, iPod touch and iPad, I can confirm that this at least didnít worked for me. But then again I got lots of messages from Twitter and email from users who said that they got it working on iPhone 3GS and all. But at least in all my tests, it didnít work for me even on an iPhone 3GS."
Now, let me explain why people may luckily get it to work:
1) Notice step guide #8: "Add the 220.127.116.11 gs.apple.com line to the host file." That tricks Itunes into contacting Cydia server instead of Apple's servers. Do you know why? Hint: SHSH hashes.
2) Here's the important thing. Saurik, Cydia guy, says about it: It seems that more shsh are on file and even some of you that havent ever jailbroken and just got a new iphone may actually have an shsh on file. Itís definitely worth a try to set up Saurikís signature server in your hosts file and try to restore that way. You may get lucky and get a downgrade even on a new device.
Once again, there is no magic / trick to downgrade without SHSH hashes saved for 3GS or IP4.