Leaked OS 10.2.0.483 [Z10] STL100-2/3/4 and SQN100-1/2/3/4/5
 

New OS

You have to download and install 10.2.0.341 before installing this version.

Should leave you with the current OS version (483) while using the radio from 341.

You can download 10.2.0.341 here from BlackBerry (make sure that you choose the right version for your handset)

Dev section BlackBerry