I am running 3Gs 3.1.3 with a baseband of 5.13.04 and according to http://jailbreakmatrix.com/iPhone-iTouch-Jailbreak I can upgrade (tethered) to 4.2.1 and it says it is unlockable using ultrasnow. Is this in fact correct - all I have to do is use the custom firmware link on that site and that will preserve my baseband? Or do I have to do something else to preserve it? (tiny umbrella?) Thanks in advance.