After excellent support play between Brunger, lock Hunter Gibson, prop and captain Konradd Newland among others, the gap opened out wide for fullback Monty Sherriff to put winger Simione Tarogi over in the corner.
Staying on attack, Whanganui charged at the line through their No 8 Judah Saumaisue, and after swift recycles, Brunger ran at the gap to score his double for a 20-0 lead.
However, Whanganui weren't having much luck with conversions, so Centurions closed the gap against the run of play when, after recovering the restart and getting a couple of penalties, they were able to attack the line and score under the posts for an easy conversion.
Whanganui struck back quickly as Sherriff made a great run from the sideline to midfield, leaving defenders sprawling, and the ball was transferred quickly to the far side, where Tarogi threw the dummy and powered through two tacklers and scored, with first five Pita Manamanaivalu taking his turn at the kicking and finally getting some extras on the board.
But as the rain fell more steadily, Centurions came roaring into the second half, barely missing tries in each corner through being held up and a fumble respectively.
Mistakes were holding them back, but a succession of penalties kept them on attack and, eventually, the possession told, with one of the forwards forcing the ball down beside the posts, another simple conversion making it 27-14.
Whanganui went from concerned to worried when, with a gap in the line due to an injured player, Centurions moved the ball and got a penalty, taking a tap for their reserve winger to score in the corner, the kick going wide.
With momentum against them, Whanganui needed something and they got it when Centurions spilled the kickoff and then a high tackle led to a yellow card and a chance for the home side to kick into the corner.
While the scrappy lineout ball fell on Centurions' side, sharp Whanganui flanker Isaac Jordan dashed through and dived on it to score, reserve halfback Petera Koro slotting the conversion for a priceless 34-19 advantage.
But soon, the home side were trapped back in their 15m as Centurions rode a mounting penalty count for the pack to drive over and score.
A chance to push for the winning try was stopped, and then Whanganui were reduced to 14 men themselves through a yellow card for a stomp on attack.
Centurions got out of their danger zone and a penalty saw them on attack, with the forwards again getting in behind their ball carrier to score, although they were again unable to land the conversion.
With less than two minutes left, Whanganui held Centurions just inside their own half and got the crucial penalty to take the tap and boot it out to hang on for a victory.
Around the grounds
GIRLS: The Whanganui Under 15 Girls played a "Game of Three Halves" in Masterton on Saturday. They picked up a 14-0 win over Wairarapa Bush but lost to Manawatu 33-0.
TRY RECORD: Alekesio Vakarorogo's four tries against Buller equals the Whanganui Heartland record for tries in a game. The others were Pati Fetuia (2006 vs Thames Valley at Cooks Gardens), Cameron Crowley (2008 vs East Coast, Cooks), Te Rangatira Waitokia (2016 vs Poverty Bay, Gisborne) and Tyler Rogers-Holden (2019 vs East Coast, Cooks).
