IOS rev12 will over write rev13b so yes you can.
I was trying to find out more on installing ios222 or ios223 and found this http://gbatemp.net/index.php?showtopic=160973 It don't say much about it but it might give you a hint of what to do. So take a quick look and post any good settings.
I was trying to find out more on installing ios222 or ios223 and found this http://gbatemp.net/index.php?showtopic=160973 It don't say much about it but it might give you a hint of what to do. So take a quick look and post any good settings.