I've got a 16GB 3G that was running os 4.0. I downgraded to 3.1.2 using the downgrade guide on Lifehacker and then ran blackra1n and blacksn0w. I'm a jailbreak/unlock n00b so I didn't know/understand of the modem firmware issues, and I've now got a 3.1.2 device unlocked but with 5.13 modem firmware. I'm trying to find what options, if any, I have for downgrading to 5.12 or earlier but am still confused on whether or not it's possible at all and if so how to do it. So is it possible? And if so, what do I do?