The PTCRB website has just certified a new firmware update for the Sony Xperia SP (C5302, C5303, C5306). Firmware build 12.1.A.0.253 is expected to be the Android 4.3 update and compares to the current build version 12.0.A.2.254. Given the certification date, we may even end up seeing this arrive before the year is out. We’ll keep you posted.
Thanks Christian, Mischell53 and Patryk!