Cox, 25, in his rebuilt Taslo Engineering Mitsubishi Evo X with local co-driver Sarah Coatsworth, said he was happy with the result after a flat tyre on Saturday cost him two minutes of stage time.
"It was an awesome event and this opening round was more about testing the car out because we weren't really sure how it would go," he said. "I'm very happy though - the car went at 100 per cent and I just wanted it to make it through.
"It was unfortunate on day one - a sharp stone got caught in and it was always going to be difficult making up that lost time."
Cox had an improved day on Sunday - including a 47km long stage win.
"Day two was much better and it was great to take out that big stretch," he said. "There were still a couple of mistakes - I slipped off road and rode through a farmer's fence which was interesting but overall I'm pleased with the finish and it's a good amount of points to take from the first round," he said.
Cox, who entered his first New Zealand Rally Championship at just 16, said he was feeling confident ahead of the next round - the Rally of Whangarei at the end of this month.
"Now that the car has been rebuilt and I'm happy with it I'm just fully focused on the next event," he said. "Whangarei is a course I'm confident on but I'm going to make sure I do a lot of preparation. I'll be watching a lot of footage of the track so there'll be no surprises."
Last year Cox finished second overall in the New Zealand Rally Championship, after a three-year break from the competition. Cox said he wanted to go one better this season.
"I'm expecting this to be a good year. I've done a lot of driving with Sarah and we're a good team together," he said. "This year the competition is a lot stronger with the quality of drivers in the field but we are aiming for the win. It's my second year properly back, I'm feeling refreshed and ready to go."
New Zealand Rally Championship, Rally Otago results:
1. D. Holder / J. Farmer (1)2:48:38.0
2. A. Hawkeswood / J. Cress (6) +45.9
3. R. Gardner / A. MacKay (14) +2:03.4
4. G. Featherstone / D. Devonport (10 ) +3:03.5
5. S. Cox / S. Coatsworth (4) +4:02.7