So you have v20 baseband.
4.0.3 ICS = v10
4.1.2 JB = v20
CM10 need v10 baseband
CM10.1, 10.2, 11 need v20.
So if u want CM10 download v10 baseband and flash it in CWM just like ROM then CM10 will work
I would tell you to flash CM10.1 is much better and battery life is awesome and you dont need to change baseband because 10.1 work on v20.
How do i flash the correct gapps?