Expectations were kept realistic for the new second-five and fullback playing at this level, but other than Kuruyabaki making a couple of hiccups which led to Taranaki's second half tries, the pair were outstanding with their handling and line-carrying - making smooth breaks and excellent cover tackles.
Kuruyabaki pumped his way through defenders for two tries from close range, while Waitokia swooped in on a long Taranaki pass and dashed 85m to take his team to a 24-0 advantage and send the home side from concerned to outright panic.
Among the other newcomers, flanker and tryscorer Campbell Hart had a brilliant game, while looming lock Gavin Thornbury will be a true weapon during the Mitre 10 Heartland Championship, especially on days when the wind does not take the lineout ball sideways.
The only concern was the leg injury to first-five Craig Clare, who looked sharp in the opening quarter, although Wanganui lost little with Dane Whale coming on to carry the can.
Captain Peter Rowe was pleased they kept composure turning to face the howling wind and rain, even scoring the last two tries of the match.
"To come out and defend like that, it's a base to build on. The fact we can finish strongly is good.
"[The weather] probably was to our advantage as it slowed it down a bit - they couldn't get the flow."
Coach Jason Caskey could not have asked for a better confidence boost for this weekend's Ranfurly Shield challenge against Waikato in Hamilton.
"Pretty happy, a lot of stuff we wanted to do but didn't get going with ball in hand.
"We forced them into mistakes and took advantage."
Caskey praised the young backs for stepping up mentally and physically for the higher standard.
"Kameli, he was great, and Te Rangatira was really good as well."
Right from Clare hammering Taranaki No8 Kolaia Nalewabau with the game's opening tackle, Wanganui were on top.
While Taranaki had some dangerous players like hard-working fullback Jayson Potroz and big winger Pita Sowakula, their chances were few and far between with plenty of dropped ball and penalties on both sides.
Tuimauga, Hart and lock Sam Madams played for keeps with their tackling.
A beautiful Waitokia pass to winger Michael Nabuliwaqe had Wanganui in striking distance and after a series of probes, Kuruyabaki cut back infield and kept his feet to be driven over the line.
Taranaki winger Tayler Haskell spilled a long Wanganui clearing kick and from the 5m scrum, Nabuliwaqe hit the short ball at pace, with the ball fed back to Hart to drive over the line.
Hart burst through midfield after a quick Wanganui lineout and while the ball went to ground, Kuruyabaki picked up the bounce and forced his way across the chalk.
Taranaki worked into territory off some Wanganui fumbles in the wet, but after being stonewalled on defence, they tried the long pass which Waitokia telegraphed from a mile back and no-one was going to catch him with a 15m head start after the intercept.
After Wanganui were held up on a drive over the line, Tuimauga and Tofa dealt the ball between them to get another crack, giving busy halfback Lindsay Horrocks the perfect chance to throw the dummy and dive over the ruck and score under the posts nearing halftime.
As expected, Wanganui had to live on defence as the rain and wind intensified in the second half, but their tackling and time on the ball was making Taranaki desperate.
The hosts got one back when Haskell snatched a Kuruyabaki cut-out pass to race to the other end, then Taranaki centre Ben Leng scored in the far corner after a fumble at the back saw the Wanganui second-five have to rush a shallow kick into the breeze from behind his tryline.
But the home side got no closer than 31-12 as it was the amatuers from the Heartland who showed superior conditioning in the final minutes.
Kuruyabaki redeemed with a big run down the sideline, finding Waitokia to cut back infield, then reserve flanker Jamie Hughes carried the momentum on and reserve hooker Cole Baldwin smashed over to score, with Whale adding a good conversion into the breeze.
Whale tapped another penalty and Wanganui grubber kicked ahead, with the slippery ball changing hands between both teams on Taranaki's line before Madams claimed it as his own to score on fulltime.
Wanganui 43 (Kameli Kuruyabaki (2), Campbell Hart, Te Rangatira Waitokia, Lindsay Horrocks, Cole Baldwin, Sam Madams tries; Dane Whale 3 con, Craig Clare con) bt Taranaki Development 12 (Tayler Haskell, Ben Leng tries; Jayson Potroz con). HT: 31-0.
