Fuzzyband 4.0 b1-3 ,Easily check your boot

This new edition is compatible with 3.1.3 code (3G and 3GS)
You can easily downgrade your baseband if it's possible,tryed on 3G with modem 5.12.01 (offcourse can't downgrade it)
Go cydia--categories--system--fuzzyband (that's the terminal version);)
Enjoy!