I just did mine after it threw an error code. I was getting a lot of pre-ignition explosion, and especially in high gear (6th) and lower speeds, car was undriveable. I changed the first lot of spark plugs at 37k km (2013) and this at 82km. There was a lot for carbon build up and the 2nd cylinder which threw the error code and forced the car into limp mode was pretty bad with terminal touching. I also had the 6th one bad too but not registering error codes. I hated driving the car.
Since the change it has been like new with smooth acceleration and just singing. Like the other OP said, not going to wait for this long to change. It took me about four hours for the job without removing the airbox. Getting the ones close to the firewall was time consuming and frustrating. Anyway, it's done for now!
