Land Rover Repair: Disco II CAT & Oxygen Sensor Replacement, o2 sensors, oxygen sensors

Question
I have a 2000 Disco II and replaced all four oxygen sensors and the CAT Y pipe, all LR original parts. I've heard that calibration is needed for the new parts to function correctly with the ECU. Also noticed that my car started holding on to gears longer before it shifts, could this be related perhaps. Can you tell me if this is true, and if so if it can be done myself? Thanks

Answer
No calibration is needed when you fit a new catalyst and o2 sensors.  If the truck shifts differently right after doing that, look your work over carefully for the answer. . . something unplugged . . .bent . . . damaged?

If the repair was done right the transmission should not have been affected at all.