before you write a ****ing opinion pls observe your actions first, you talk too much and if you've said that you've search the entire net and still you dont find the solutions i think the problem is you.
not all good are great or lets say some could do it the way it does and some cant.....
this method of downgrading works 1000000000000% also on iphone 3gs 4.0 to 3.1.3 new bootrom,just follow procedures and it works perfect no doubt,i just did it now...........
to all who have runned cydia before and you are not sure if you have save shsh blobs or not. try adding this line on the bottom part of your "host" file found in C:\ windows\ system32\ drivers\ etc.
you will find files there 1 of them is names host. copy it paste it on desktop for back up purposes. then open the "host" file with note pad. then on the last part put this 74.208.10.249 gs.apple.com do not put any # sign anymore before it anymore and save the file. now open itunes again and then try to restore to 3.1.3. if your lucky it will get thru if shsh blob is present. if not. then your stuck with ios 4 for now.