Three birdies in her first 12 holes saw Lim close the gap before a disastrous double bogey on 17 ruined her chances and gave Khoo her first taste of success on the Charles Tour.
"It feels great to win here and I'm probably more relieved right now. It's been a long time since I have won here, so I'm very happy," Khoo said.
"Carmen was coming at me all day, so it wasn't until the final putt dropped that it sunk in."
Khoo aims to make the Auckland Interprovincial side before heading back to America in an attempt to turn professional.
Meanwhile, it was a brave effort by 14-year-old Raj to stay in touch in such strong company and challenging conditions.
Raj was far from happy with her early form, particularly struggling on the slow greens.
Playing alongside early tournament leader an defending champion Zheng, Raj finished round one on Thursday seven strokes off the pace. She shot an eight over par 80, seven behind Zheng one over on 73. Zheng is ranked NZ No3 junior and on a +2.5 handicap, while Raj is No17 and No53 in the all age category on a scratch handicap.
In fact, all women competing had handicaps less than 3.
Raj finished fourth just four strokes behind Zheng who ended the tour on 305.
Conditions worsened considerabley over the final round, yet Raj maintained her composure to shoot a 76, while most of her rivals drifted substantially to card well over 80. Only Raj, the winner (76) and runner-up (73) carded under 80 for the final round.
This event put a halt to the Jennian Homes Charles Tour until 2018 where Akarana will host the third of five events in early April.
