"We lost eight minutes in one stage [last year] when we had a belt come off the car and had to stop and change it," he said.
He still managed a top 10 finish and won three stages outright.
"We were one of the fastest down there last year so it's promising for this year."
He said going into his first attempt at the event in 2016, he thought a lack of local road knowledge may have been a disadvantage.
"But from the start of the rally we were one of the quickest. The roads are quite similar to the roads around Rotorua. You are racing on forest roads more than public roads in farmland. Last year I felt really comfortable driving on those roads because it was what I am used to and we think we can be right at the front again."
Much of the five weeks between rallies has been spent addressing the turbo problem and rebuilding the engine to fix the damage caused.
"We were a little bit behind time because we had to wait for parts coming from America for the motor, but now we have a newly rebuilt motor and the turbo has been redesigned so it shouldn't happen again."
Cox is looking forward to the night stages.
"When I first did [night stages] I was really unsure about them, but I still had really good speed at night."
Coming at the end of the rally, the two stages could easily shake things up in the final standings.
"For some it's a bit of a curve ball in the rally because some people will lose a lot of time and some will make a lot of time up - so it could mean a bit of a change to the end results in the last two stages."
Cox knows that getting a good points haul in Canterbury is crucial if he is to equal or better last year's series placing.
"I'm still going to try for that. We are lucky that this year the last round is a two-day event, so you're not really out of it before the last event and there's a chance to make a good comeback.
"I'm positive we're not out of it yet, but we do need to get some good points over the next couple of rounds to get back into it.
"This year has gone well speedwise, we just need to put everything together and get that final result."
The rally starts in Rangiora at 8.30am on Sunday.