"To all our sponsors and our fans for sticking by us and my team, myself, the team have stuck by me, fixed all my issues and everything I've been complaining about and it is the best crew.
"I'm so happy."
Mostert (1:13.5737) will start from second on the grid for the 70-lap race with Reynolds (1:13.8378) and Shane van Gisbergen (1:13.7456) behind the front pair.
Championship leader Winterbottom will start from fifth he could only manage a 1:13.8618.
He'll start alongside nearest rival Fabian Coulthard.
Defending series champion Jamie Whincup missed the shootout and will have to start from the middle of the field in 13th.
It's even more dire for his Red Bull Racing teammate Craig Lowndes, who will start from a lowly 23rd on the grid after a disastrous qualifying run.
Sunday's race starts at 6.15pm NZT.
-AAP