On geohot's blog he says the following about the downgrade.
Does anyone know how to downgrade the baseband from 4.24.02?Here is a bspatch file to be applied to ICE2_02.28.00.fls allowing downgrades from 2.30.03 using BBUpdaterExtreme. By replacing the patched cert with your current run cert, you can downgrade from any other version.
I have a 5.8 bootloader.
Thank for any advice.