"Sometimes we are quite brutally honest with each other," he joked.
Gus had been playing golf for almost a year and Nathan, 12, had been playing for the last three years.
The pair often played together on the Mount Maunganui Golf course with their younger brothers.
"We are all out here most days after school," Gus said. "We all motivate each other."
The AIMS tournament was played across four days at four different golf courses at Ōmokoroa, Te Puke, Tauranga and Mount Maunganui.
Nathan said the greens on the Tauranga and Ōmokoroa courses were "pretty hard".
"The greens can be quite deceptive," Gus said. "It is hard going from fast to slow."
But Nathan said he had set goals for himself to help get him through the four rounds.
"I just tried to do my best in all of the rounds," he said.
Both Gus and Nathan said they wanted to become professional golfers when they finished school and liked how the game challenged them both physically and mentally.
"It is very good for my temperament," Gus said.
"It can be very challenging. I like the fast nature of it."
AIMS Games golf coordinator Mike Campbell said AIMS Games was a platform for intermediate-aged golfers to play in their first big event.
"So many of them go on to do bigger and better things," he said.